Jimmy G

Hi Kye, wow, what an in-depth look into this camera...methinks you're very interested to the point of becoming a future owner?! 😉
I'll reserve my points to "output quality" as each of the internal mechanical aspects and features of the camera will appeal (or not) differently to individual users.
To that end, you've covered quite nicely (and better than I have been able to do) the need for wider dynamic range when shooting outdoor environments...the f/stop range on a typical sunny day is just too much for 8-bit Rec709 to contend with for those of us who need/desire/require that the sum of our frame includes everything from the brightest clouds and specular highlights to the detail and vibrancy going on in the shaded regions. Our eyes capture all of that and I have never been ashamed to ask for and seek out equipment that gets me closer to being able to capture that same natural view. I laugh every time I hear/read someone say that this is niche...no more niche than what I came to expect from my old love, Kodachrome 25! LOL
Getting to understand how HDR and 10-,12- (14-, and 16-) bit imaging can help "get me there" has been a challenge up to now...hard for any of us to realize the benefits of these things when viewed on SDR monitors! Ha! Enter my new M1 Max Macbook Pro with its HDR panel, I've devoted this year to finally educating myself on what is possible (and desirable) with the 10-bit footage I've been accumulating with my S1 for the past few years...in fact, I've decided to hunt down a used Ninja V just so I can become familiar with using 12-bit ProRes RAW at learning what it might and might not be "most practical for" for my style of nature shooting. Clearly, not every situation calls for such bit-depth or, even, DR and learning those lessons through shooting will help educate and inform me as to when varying codec choices are called for...all the more reason for my wanting it all internal to the camera (GH6 and future releases), call up a Custom setting and off one goes, er, shoots, no fuss no muss (f*** external recorders, really, I mean that from the bottom of my heart, Panasonic).
Anyhoo, I thought this article and the accompanying two videos would be of particular interest to you (and to all our fellow folks trying figure out the whens and whys and needs for HDR and high bit-depth)...a two-part interview with Kevin Shaw, CSI and founder of the International Colorist Academy (ICA), where he demonstrates where and how the benefits of HDR acquisition come into play...
Is 2022 the Year You Buy Into HDR? - Frame.io Insider
https://blog.frame.io/2022/01/17/hdr-in-2022/
...a college-level education from someone who knows. 😉
 

Yep. Very important to me also.
I’m not opposed to change other than when it’s change for change sake or because the new latest thing ‘might’ make a difference.
Another yep. That’s one of four options potentially that I may sometime in the future switch or upgrade to:
Fuji XH2
Panny S1/S5 line ii
OM-1
Sigma FP next gen
But as above ONLY if there is a compelling enough reason for me to do so that makes it worthwhile as changing an entire system is a pain in the ass on so many levels, but principally familiarity.
GH6 is also potentially on the table, but right now, the OM Systems option has slightly more appeal…
For video, either of the current 4/3 options could easily meet my needs, it’s just the stills side that concerns me.
I have had various 4/3 cameras before but they fell slightly short compared with Fuji APSC I was using at the time, so compared with 24mp full frame, never mind my 47mp S1R…
I could easily switch back to 4/3 for video without testing as it’s a known quantity for me, but for stills, I’d need to run some tests.
Fortunately, all/any change is off the table until at least this next Winter!

On what I shoot I'm everything... director, cinematographer, audio tech, editor, colourist, and Head of Distribution.
You'd think that would make things easier, but it just means that instead of a room full of people all blaming each other and feeling good about their own work, I just sit quietly wondering what went wrong and wishing I was better at literally everything!
That's probably pretty easy.
Shoot a few test shots, then just adjust the curves to get the right output.  Specifically, Hue vs Hue, Hue vs Sat and Hue vs Lum.  You'd be amazed at how powerful those are.  if you start with Contrast/Pivot/Sat and then do a pass on those Hue curves you can really get a good grade very simply and easily.  
I use them a lot when grading videos from here in Australia where the grass is almost always patchy and somewhere between lush green and straw yellow, and trying to get a shot-to-shot match when you're pointing in different directions and seeing different bits of lawn.
The final season (and one episode especially) of the show was so dark that it was difficult to follow what was going on in the show - it was a social media shit-storm, the cinematographer blamed the viewers:
https://mashable.com/article/game-of-thrones-too-dark-cinematographer
and websites got a lot of mileage talking about how to re-watch it so you could actually see it:
https://www.theverge.com/2019/4/29/18522550/game-of-thrones-got-season-8-hbo-battle-of-winterfell-long-night-fix-tv-settings-darkness
In reality, it was a large-scale test of how content is consumed in the real world because they pushed how dark the final grade was (which was appropriate to the narrative and subject matter), and the answer was that basically the entire pipeline isn't setup for dark things to even be visible, let alone somehow ..  "accurate".

Walter Volpatto also mentioned that he's never been asked for a HDR output that wasn't limited to the P3 colour space, so it seems that you're right that 1000 nit P3 is becoming the standard.
Colour accuracy is a pipe dream and (besides "how can I get my iPhone to look like an Alexa") is the topic that gets the colourists the most excited.  
The best approach that I've seen the colourists take is:
grade on a calibrated display keep a calibrated consumer-grade 709 display handy and check it every so often to make sure you're not doing anything stupid get whatever display the Director is viewing your work on and check it on that too once it leaves your studio, forget about it whenever someone important (other than the Director) starts yelling at you incoherently about the colour being completely screwed, arrange to have them visit your studio and show them what it looks like on your reference display and make sure to explain in great detail how expensive and calibrated everything is If you want to talk about accuracy, let's start the conversation discussing the final season of Game of Thrones......
It seems to be an approach taken by other manufacturers too - shoot a scene at "correct" exposure on multiple models of their cameras using their standard log profile and you should be able to pull all the footage into post, apply their LUT or CST, and everything should match across all the cameras.  
Canon did that with the XC10 - matching it to the C-series line, which was why it took the same ridiculously expensive media as the C200/300 but didn't use the cards to even remotely near their performance, and used the C-Log profile but didn't use the full 0-1024 values but instead mapped the XC10 limited DR to where that DR lined up with the same values coming from a C500 or whatever.
In the case of the XC10 it meant they basically crippled the camera for the sake of compatibility, but it would have been great to be able to use these for BTS and reference use (which seemed to be something they did) and not have to have a separate colour pipeline in post, which would have been really useful for the VFX folks who might want to see the setups and might also want a colour reference from that.

If you're looking for color accuracy, you'd probably be better off looking at a Sony camera and use one of their picture profiles. Their neutral profile always seemed pretty accurate and allowed a little wiggle room to adjust contrast and saturation to taste.
Or maybe grab a camcorder. I feel a lot of people would be better off with a camcorder for video than mucking around with Log profiles in photo cameras.

Funny you mentioning Jon, I've been following his own HDR explorations and experiments over at his Deajeon Chronicles web pages...
HDR – The Daejeon Chronicles
https://daejeonchronicles.com/category/hdr/
...seems, like many of us, he's trying to sort through the changing landscape from 100-nit SDR to 1000(and beyond)-nit HDR.
I agree, the various standards (Dolby, ACES, HDR1000, or even just going home-brewed as many seem to be doing, etc.) gives one good reason to pause and try and figure out the best path forward. These are not inexpensive choices even at the Indie, Wedding, Boutique, and (cough) Prosumer levels, etc. and methinks we're all looking for a sensible and affordable pathway forward for ourselves.
Say what folks may about iPhone with Dolby Vision, in its own way it is helping folks visualize where and how both the increased DR and luminance will look and help better the understanding of "what it is" and "what it offers" from both the creation and consumption sides of things. These truly are exciting times for those wading into the mix!
From my studies and observations of the current use of the technology it seems as though 1000-nit DCI-P3 is where things are currently settling for home distribution and consumption. And that, depending on how important it is for the creator to see their grading choices being fully (or as nearly fully) seen accurately with their consumers will fuel their choices (decisions) per Dolby Vision vs ACES vs home-brew, etc..
It seems to me that if color accuracy is mission-critical for one's client (or one's personal standards) then finding the appropriate end-to-end solution will require more thoughtful decision making for one's gear investments. While I do not have to work with corporate branding folks or particular wedding clients for whom color accuracy might/will be paramount, I do run into enough color inconsistency with gear for my outdoor shooting that I would very much like to improve upon. I can't tell you how bad many camera sensors I've encountered when challenged with this seemingly innocuous target...
violet flower at DuckDuckGo
https://duckduckgo.com/?q=violet+flower&t=h_&iax=images&ia=images
...hint: those images are mostly all wrong! Ha! Color is not a minor or inconsequential thing for this user.
That said, I am very pleased with how my S1 handles the majority of color situations for my needs, and I am greatly encourage to hear from Panasonic that the color coming out of the GH6 will be able to use the very same V-LOG LUTS as the S1, S1H..."Thank you!" Panasonic engineers for getting that new MFT sensor to perform so closely with your FF sensor!
My goals for this year are to learn how to shoot and grade for 1000-nit DCI-P3, so, for me, getting accustomed to and familiar and comfortable with the wider DR and increased luminance and color information will likely be the biggest areas for that education. 🙂

<<
The LUMIX GH6 offers the renowned colorimetry of the VariCam line of cinema cameras and uses their V-LOG picture profile and wider V-Gamut. For monitoring your work and to see an image that is no longer in LOG, the GH6 includes the V709 LUT (Look Up Table) with Rec.709 standard in the camera by default, this LUT can be output over HDMI or to the cameras monitors or both. It is possible to install your own LUT’s into the GH6 and access them from the V-Log View Assist menu. For users of the Varicam and EVA1 the GH6 can support LUT’s in their .vlt format, and for users of other camera systems we also support the .cube format.
>>
From Panasonic's GH6 Press Release here...
The LUMIX GH6, a Compact Next-generation Mirrorless Camera Featuring Unlimited C4K/60p in 4:2:2 10-bit, 5.7K/60p in 10-bit and 4K 120p HFR / FHD Maximum 300fps VFR Video Recording | Panasonic North America - United States
https://info.panasonic.com/news/lumix-gh6-compact-next-generation-mirrorless-camera-featuring-unlimited-c4k60p-422-10-bit-57k60p-10
 
And these were the Panasonic VariCam LUTS to which I was referring...
VARICAM LUT LIBRARY | Support | Cinema Camera Global | Panasonic
https://pro-av.panasonic.net/en/cinema_camera_varicam_eva/support/lut/index.html

<<
The LUMIX GH6 offers the renowned colorimetry of the VariCam line of cinema cameras and uses their V-LOG picture profile and wider V-Gamut. For monitoring your work and to see an image that is no longer in LOG, the GH6 includes the V709 LUT (Look Up Table) with Rec.709 standard in the camera by default, this LUT can be output over HDMI or to the cameras monitors or both. It is possible to install your own LUT’s into the GH6 and access them from the V-Log View Assist menu. For users of the Varicam and EVA1 the GH6 can support LUT’s in their .vlt format, and for users of other camera systems we also support the .cube format.
>>
From Panasonic's GH6 Press Release here...
The LUMIX GH6, a Compact Next-generation Mirrorless Camera Featuring Unlimited C4K/60p in 4:2:2 10-bit, 5.7K/60p in 10-bit and 4K 120p HFR / FHD Maximum 300fps VFR Video Recording | Panasonic North America - United States
https://info.panasonic.com/news/lumix-gh6-compact-next-generation-mirrorless-camera-featuring-unlimited-c4k60p-422-10-bit-57k60p-10
 
And these were the Panasonic VariCam LUTS to which I was referring...
VARICAM LUT LIBRARY | Support | Cinema Camera Global | Panasonic
https://pro-av.panasonic.net/en/cinema_camera_varicam_eva/support/lut/index.html

I follow jonpais on my email, not a big fan of his attitude overall but he seems to be pretty good with the HDR stuff and it looks like it is a Very expensive way to go. Not counting hard to edit on and on.
 The only thing I have that does HDR is my iPhone, and I don't use it much because of the damn Dolby Vision thing. I hate this crap with so many different standards. Drives me crazy. But I have a BenQ 32" 4K monitor I can see it on, probably not that good to edit HDR with though, unless you buy a super high end monitor.

I'm truly not concerned about availability, seems these are fairly easy to locate used.
True that, the S1's output both for stills and video is much more than "good enough" for my nature/wildlife/birding needs.
Where I'm at right now is a restlessness to improve upon what I'm doing right now, whether it be through weening myself off of the Rec.709 output workflow (and moving into DCI-P3 via HDR Rec.2020 for an HDR1000 target) or finally providing myself with a crop-sensor companion (that compliments the S1) for those shooting outings where it becomes the better tool than the FF sensor. (For my needs the 5DII/7D, then a7r/a7sII/a6300 combos covered my needs, so I've been, er, "circling the airport" the past couple of years trying to answer "S1/? combo" for myself.) Trust me, both of your recommendations have been bouncing around in my head for some time now! LOL
As for the GH6, it is most certainly providing users with a robust (and compelling) feature set in regards to its video output capabilities straight-out-of-the-box, the wealth of 10-bit All-I and ProResHQ options has my serious attention!
Internal RAW needs to be a priority here for team Panasonic, their competition is now making it a "thing" and it is (and will be) the deal-breaking, er, "killer app" for those of us who require dongle-free simplicity and stealth...especially as the GH6 ages through its life cycle.
FWIW, I've already let Panasonic dangle (and entice me into a purchase with the possibilities/potentials of) an internal high-speed bus and XQD/CFExpress slot with my S1's and then not deliver on those possibilities and potentials even with some token and/or heat-time-limited ProRes or RAW recording options. So that, um, "failure to deliver" has now become a factor in my decision-making and a part of me is now loathe to volunteer myself again as a full-MSRP early-adopter for them again with this new release.
"Fool me once, shame on you...fool me twice, shame on me" and all that.
Either choice (i.e. learning how to shoot for and process for HDR1000 with RAW with a ninja and my S1's, or having more pixels-per-duck and 300fps and ProRes HQ and learning how to target HDR1000 at more than thrice the price with a GH6) exciting times ahead with where I can take my learning! 🙂

The GH6 is in stock at my local camera shop in Dublin, Ireland, where I bought my GH5 when it was first released. If I wasn't living on the other side of the world, literally, I think I would pop in and pick one up to see what all the fuss is about.

@Jimmy G My two cents:) Dont buy a Ninja V. Your S1 does good enough without it.
So either keep the S! and save your money or sell it and get a GH6. Like I said, my two cents. 🙂
Or keep the mighty S1, still buy a GH6 and compare the two.:)

You had better buy a used Ninja V now before everyone else does!  😬

User manuals (English full, English Quick Start Guide and French full) now up in UK...
DC-GH6
https://support-uk.panasonic.eu/app/products/detail/p/28412

Well, egg on my face, I missed the whole "conforming to 24P" thing on my first read, thanks for the clarification...sometimes this "old boy" needs a smack on the back of the head! LOL
 
 Thanks for bringing this point up, as well, I'm thrilled to see Panasonic address this issue (in part) with some of the higher bit rates on the GH6 for all of the reasons you state. Learning to recognize which scenes will suffice with "good enough" and which scenes will require a, er, "heavier hammer" is an individual process, and it will be nice to finally see what ALL-I brings to the table for my needs as it's been something sorely lacking on my S1's. (Tap, tap, tap, Panasonic, if you're listening, this might be something you could finally provide for for my S1's expensive CFExpress cards? Maybe toss in a little of that "GH6 ProRes goodness" while you're at it?! Ha! The poor cards have been sitting idly by in their slots for the past few years wondering why I bought them. LOL >cough< Firmware update?!)

Well, as more and more content is being consumed will continue to be consumed on HDR devices (like OLED, QLD, smartphones and computers) I'm surprised at this response. My read on deliverables is that SDR has not only been "shown the door", it is being gingerly escorted out. It's why I began to shoot 10-bit with my S1's and have been an online hound-dog for internal 12-bit. As I mentioned to a (well-known) Panasonic rep at PDN Expo back in 2018 why I wanted this in their cameras, "just because I can't see it now (in the SDR realm) doesn't mean I won't be able to see it when 10- and 12-bit monitoring and consumption become the norm in a few years, I don't have the luxury of hopping in a time machine to go back and "refilm that solar eclipse" or "eagle snatching that fish" in 10- or 12-bit. However, if I shoot that today for HDR I can always come back in the future to make it shine!"
As the saying goes, "skate to where the puck is going to be".

OT (apologies, Kye)
I suspect using Resolve Studio might be my easiest path forward for access to a CIE Chromaticity scope until the kind folks at Apple understand the importance of visualizing one's chromaticity spaces rather than rely on such functions as (oh, say) poorly documented broadcast-safe overlay filters (I will continue to look into whether an FCP plugin might be available for this). It's important (well, to me) to know where my out-of-gamut acquisition RGB colors are falling to better inform my decisions on what I can or should be doing about it with a grade...perhaps I'm over-thinking it at this point in time but I'm trying to build a working knowledge of what exactly is going on with color space chromaticity and dynamic range (real nerdy stuff, ha!).
To your ebay suggestion, thanks, I was unaware that folks were selling their unneeded/duplicate licenses like that...my Resolve license solution was to buy their Speed Editor and get the activation card free. All "down the road" stuff for me as I'm already dropping too many potatoes off my plate! LOL
We return you to our regularly scheduled broadcast...

OT (apologies, Kye)
I suspect using Resolve Studio might be my easiest path forward for access to a CIE Chromaticity scope until the kind folks at Apple understand the importance of visualizing one's chromaticity spaces rather than rely on such functions as (oh, say) poorly documented broadcast-safe overlay filters (I will continue to look into whether an FCP plugin might be available for this). It's important (well, to me) to know where my out-of-gamut acquisition RGB colors are falling to better inform my decisions on what I can or should be doing about it with a grade...perhaps I'm over-thinking it at this point in time but I'm trying to build a working knowledge of what exactly is going on with color space chromaticity and dynamic range (real nerdy stuff, ha!).
To your ebay suggestion, thanks, I was unaware that folks were selling their unneeded/duplicate licenses like that...my Resolve license solution was to buy their Speed Editor and get the activation card free. All "down the road" stuff for me as I'm already dropping too many potatoes off my plate! LOL
We return you to our regularly scheduled broadcast...

People with the desire for a fundamental but affordable update could buy a GH4 for 500 USD or a Lumix G9 with the free 10bit update  for 800. These cameras are in the league and much more. @Django GH6 is rather in the league of A7s3 if specs deliver what they promise with that innovative screen, class leading IBIS and more, 5.7K60, minus the DOF from the FF sensor with the same lenses. Give it an affordable focal reducer for around 100USD and you are in S35 land. Wished they had given the GH6 a S35 sensor with the choice of a MFT crop

I bought my Resolve Studio 17 for $145.00 on ebay. Lots of people sell them when they buy the Blackmagic.controller. It's just a credit card looking thing now you get.

I think the GH6 is a triumph of incremental upgrades that provide a real difference when shooting run-n-gun video in the real world.
With the headline features so prominent, it's easy to miss the many smaller improvements that can actually make a big difference to shooting.
We talk about cameras like they're museum pieces or engineering spectacles, but often these things don't translate to the real world.  The following are my views of the GH6 from the perspective of a travel videographer upgrading from the GH5.  I've tried to include as many example images as I can - please note that these aren't fully graded and are often compromised due to me pushing the limits of what is possible from the GH5, what was possible under the circumstances, and what my limited skills could create...
But let's get some obvious things out of the way first.
Things I don't care about.....
Autofocus
The AF is improved.  People who used the GH5 AF will like the GH6 AF, and people who didn't like the GH5 AF probably won't be moved by the GH6 AF.  I don't use it, basically ever, so I don't care.  If you do care, then good for you..  move along, nothing to see here.
Extra resolution
There's more resolution, but the GH5 had enough resolution for downsampled DCI4K and lower resolutions, and the 2x digital zoom and ETC modes provided useful cropping modes as well.  The extra resolution doesn't really matter to me.
Size and weight
I care about this a lot actually, but it's not substantially larger than the GH5 from the front, which is the dimension that matters when filming in public.  The extra depth is immaterial when you have a lens on the camera.  The extra weight is unfortunate, but isn't that much and is well worth it for the fan and screen improvements.
Internal Prores
Prores is a professional codec that offers considerable improvements throughout the whole workflow.  I'm not going to say much else on this as I created another thread to talk about this but it's great to have the option, and I definitely appreciate it.  Many people were happy with the GH5s codecs, especially the 10-bit 422 ALL-I codecs, which were a shining beacon in a sea of poor-quality IPB cameras, but even those have been improved....
Huge improvements on h264/h265 codecs
The GH5 had 200Mbps 1080p and 400Mbps DCI4K, but the slow-motion modes are limited to 150Mbps (4K60) 200Mbps (1080p60) or 100Mbps (1080pVFR up to 180fps) and the effective bitrate dropped significantly when you conform your 60p or 180p footage to 24p - as low as 13Mbps!!.  The GH6 has 4K60 at up to 600Mbps (SD card) or 800Mbps (CFexpress type B) - an effective bitrate of 320Mbps, and in 1080p240 800Mbps which is an effective bitrate of 80Mbps.  
Oh, and these are all 10-bit 422 ALL-I, as opposed to the GH5 8-bit 420 IPB.
Oh, and also also, the 120p is now in 4K too.
If you're shooting sports this is a big deal as often players are in direct sunlight, depending on the time of day there might not be much ambient fill light, and any reflections from the field may be strange colours such as green grass, or various coloured artificial turf, which will drastically benefit from the 422 10-bit when colour correcting footage.  The extra bitrate is also great for having clean images when players may be bright against a very dark background really highlighting any compression nasties on their edges.  The ALL-I will be great in post too.
I'm curious to see what the 300fps looks like in real-world situations, but I've shot a lot of sports with 120p and it seems slow enough to me.
Dynamic Range Boost
This is a big deal for anyone recording in uncontrolled conditions, and especially for travel.  This isn't a vanity exercise or BS tech nerdery, this is a real creative consideration.  When you're shooting travel, the film is about the location and the experience of the people in that location, and the weather is a key consideration of this.  With the GH5 I often had to choose between clipping the highlights (ie, sky) and exposing for the people.  I also chose to expose for the sky on my XC10 and in combination with 8-bit C-Log recorded a large amount of spectacularly-awful looking footage of my honeymoon.
Here's a frame of C-Log SOOC from that debacle:

The shot was also mixed lighting with the subject in the shade, being lit by a coloured Italian shop-front immediately behind me that was in full sun....

Being forced to decide between the subject and the sky is problematic if the shot you want is "person at location X at sunset" and you can't feature that person and also the sunset.
It's also relevant for anywhere with tall buildings that create deep shade - the below is a nice dynamic image but it's a tad overdone and not how we actually see the world:

My experience with shooting the OG BMPCC / BMMCC is that their ~2 stop advantage in DR over the GH5 almost completely covers this gap.  Images with someone standing in-front of a sunset no longer feature either an anonymous shadow person swimming in technicolour-grain or a digitally clipped sky.
The GH6 DR Boost feature will help in these situations, allowing subjects to be filmed in-context rather than only in select locations were the light is just right but the scene is irrelevant.
Would more be better?  Sure.  I can hear lots of people thinking "go full frame then - moron" but the GH5 was (until now) a camera with a unique set of features not bettered by any other offering for this type of travel shooting, so while the current alternatives give with one hand they also take away with the other, normally taking away a lot more than they give.
Full V-Log
Having a colour profile that is supported natively by Resolve is a huge thing for me, as it allows WB and exposure adjustments to be done in post without screwing up the colours.  This is important because in shooting travel there are times when you can't even stop walking to get a shot, let alone have enough time to pause, get exposure dialled in, and heaven-forbid to pull out a grey-card and do a custom WB!  A great man once said "tell him he's dreamin"!
This lighting all looked neutral to the naked eye - GH5 HLG SOOC:

The advice I got from the colourists on that was to lean into it and just pick one or the other and balance to those, but sometimes the mixed lighting isn't really something you want to lean into....  GH5 HLG SOOC - look at the colour temperatures on the grey sleeve from what appears to be the strip-light from hell hanging just above their heads:

Better Low-light performance
Filming in available light in uncontrolled conditions often means needing to use high ISO settings.
This is a shot I've posted many times before, and the BTS of me shooting it, in a row-boat lit only by the floodlights on the river bank maybe 50m away.  

Notice that the smartphone taking the BTS photo couldn't even focus due to the low-lighting.

It was using the GH5 in full-auto (likely a 360-degree shutter) and with the Voigtlander wide open at F0.95.  I don't know what the ISO on the shot would have been, but there's quite a bit of noise, especially considering this is a UHD clip downsampled from 5K in-camera (200% zoom on a UHD timeline):

I don't mind the quality of the noise actually, and it responds to sharpening really well giving quite an analogue image feel, but if the image is this noisy then the colours aren't going to be at their best, and that isn't desirable.
There are a number of fast primes on MFT (ie, faster than F2) but getting sharp images wide-open is problematic, even from the very-expensive Voigtlander f0.95 primes.
The GH6's improved low-light is great, and not only does it allow recording in ever-darker environments, but it also allows the use of modest lenses and faster lenses stopped down to be within a higher quality part of their aperture range.  An extra $1000 cost on the body of a camera seems like a lot, but if it saves you $500 on every lens because you can buy slower lenses then it's an investment that has a reasonable return.
...and lest you think that the above is an extreme example, having good low-light performance is really just about filming people doing what they're doing, and in case somehow you haven't noticed, it's dark outside about half the time and people go out into it and do things.
Another example, here's a shot taken right at the end of blue-hour:

and minutes later, here's a shot showing what you can get when lit only by the light of a phone, and providing a reference for how dark this location was:

Think of the benefits of better low-light performance here.... it's very low-light, mixed colour temperature lighting, and the main feature is skintones.  The noise on the GH5, with the Voigtlander wide open is pretty brutal:

New Screen
My XC10 has amongst the nicest ergonomics of any camera and a big part of that for me was the tilt screen that didn't get in the way when using your right hand to hold the camera and the left to support the camera and manually focus the lens.  The fact that the new GH6 screen allows for both tilting as well as for flipping is great.
Contrary to what many believe, the 'flippy' screen is actually very useful for filming things other than yourself.  Any time when you cannot stand directly behind the camera is when the flipping screen is useful.  I have used it while filming out of windows (such as in moving vehicles, filming the view around the corner of a panorama framed by an arch, or taking a sneaky shot of the kids around a corner without them spotting me and pulling faces).  
Sometimes you need to hold the camera in funny ways to get a shot:

They're also very useful for those who want to take vertical photos from a low or high angle.
Fan
The GH5 never overheated on me, even in desert conditions, unlike my iPhones have on many occasions, and the GH6 will never overheat either.  It's not an "improvement" in the sense that it doesn't offer anything new, but it is a guarantee that all the extra other features won't come at an unacceptable cost.  Having a camera that overheats is just stupid, and Panasonic doesn't insult us by providing tools that aren't reliable.
Punch-in while recording
Checking focus while recording is a pretty fundamental thing, and the GH5 didn't have it (and didn't have the best focus peaking either) but now the GH6 does.  Boom.
Custom Frame Guides
The frame guides on the GH5 were worthless - pale dotted lines that were difficult to see under ideal conditions, let alone while holding the camera at arms length in a moving vehicle. The GH6 has custom frame guides that have a much more visible outline and also dim the out-of-area image, making it super easy and intuitive to use.
Frame from @Tito Ferradans review on YouTube:
 

I might be tempted to engage this for a 2.35:1 permanently and then choose what ratio to use in-post when I get to editing.  I've tried to shoot for this ratio before with the GH5, forgot and couldn't see the frame guides and intuitively composed like normal, and then downloaded the footage and found that I'd framed every shot too close for the ratio.  Fail. 
Buttons and controls
The GH6 has more programmable buttons than the GH5 (which was already great), and the extra custom slot C4 on the mode dial is very welcome.  I have my GH5 configured to be C1 1080p24, C2 1080p60, C3-1 1080p120, C3-2 4K24 (in case there's something I'd need 24p for), and C3-3 as 4K manual everything for shooting camera tests.  The first four modes are ones I want to just be one dial away while I'm out shooting, so having the extra one is really useful.
The GH5 also saved the preset focal lengths for the IBIS on a per-profile basis, so when you switch profiles you switch focal lengths.  This is important because when the camera goes to sleep it wakes up but forgets the focal length and goes back to the default one for that profile.  As such, you could duplicate profiles and use them to swap between focal lengths, like if you were recording sports on a manual zoom lens, just to name a purely-theoretical example that no-one would ever contemplate....

Better IBIS
The GH5 IBIS is great, and when you shoot with fully manual primes and without a rig, is an important function.  Having improved IBIS on the GH6 is very welcome and can really help salvage shots that wouldn't otherwise have made the cut.  One of the killer features of action cameras is that you can put them anywhere and get a huge variety of images while out in the real world, and that works for MILCs too, but if you're balancing on a chair and shooting at full arms-reach to get a shot and the IBIS isn't able to take up the slack and stabilise it, then it won't make the edit.
It doesn't matter how good the stabilisation of something is, there are instances where it will fail, and I seem to keep finding them.
USB-C port
The Prores and high bitrates will chew through storage and the ability directly record to an SSD would be spectacular.  Being able to charge the camera with USB-C would also be useful in some instances. 
In camera LUT support
I'm yet to see how this is implemented but LUTs can be great references while shooting.  You can use LUTs for things like false-colour, sure, but I'll be very interested in experimenting with ones that are very high contrast to allow for better visibility in bright conditions, and other more extreme applications that help you get the shot.
I normally use the EVF on the GH5 as it eliminates ambient light and adds another point of contact for better stabilisation, but sometimes you have to use the screen and it's not always ideal, so these could be useful for that.
Better colour science?
The GH5 colour science wasn't winning any awards, and the GH6 combination of V-Log + Prores + higher bitrates + higher DR seems to be noticeably better, which is a welcome improvement for me, especially as I am struggling to shoot in difficult situations often involving mixed WB lighting and other nasties.
The latitude tests from CineD look spectacular:



This will allow huge flexibility for imperfect shooting conditions.  Many times I pull up the shadows in an image (maybe I was trying to get the subject and the sky in the shot - shock horror) only to find the shadows a tinted awful mess.  If they look like the above then it will be tremendously useful in practice.
4-channel audio recording with the XLR module
This is slightly tempting for me.
In post I want a stereo ambient sound, and I also want a directional audio from a shotgun mic, ideally with a safety-track.  I can get either of those with the GH5 pretty easily by using the Rode Videomic Pro Plus with the safety-track feature enabled, and simply unplug it when I want a stereo ambience track using the cameras internal microphones (which are good enough if you're only using this in combination with music and other sound-design).
But the problem is that I don't know when something will happen, so if I'm recording stereo ambient sound I don't know if my subject will say something at the same time that a car goes past behind me, and I also don't know if my subject will say nothing while I'm recording directional mono audio and then before I know it we'll be somewhere else and I'll have no ambient audio from that location.  If this situation seems far-fetched, you've obviously never been on a tour bus in a third-world country before, where you might get dropped off near a small market, you then walk though the market with your group, where there is a stall every 5 steps with a different composition / lighting / and ambient sounds, and there is literally only room for people to walk single-file and you don't have time to stop at each interesting booth for a minute as you capture different compositions and audio options without losing your tour guide.  
Being able to stop for a few seconds, smile at the person there, and grab a few seconds of action with directional audio and ambient sounds would be really useful.
 

I don't fancy the added size of the module though.  
Audio screen
The GH6 has an audio button function that brings up an audio screen showing all the audio things you'd want.  Perfect for quickly checking how the audio is going.  With so much going on while shooting it's easy to forget to look at the meters OSD, and having everything in one place seems excellent.
I've screwed up the audio on many occasions, so this will be quite useful.
In summary....
The GH6 has tonnes of little improvements that I think will make it a much more useful camera when out in the field recording things in difficult conditions as they happen.  It looks like Panasonic has done a great job in not just grabbing headlines, but in actually taking the things that niggle or limit real shooters and making them better.
Now, if only the world would return to a state where I'd feel remotely comfortable wandering out into it with a camera in hand.....

I'm excited and looking forward to it! I've been cutting my teeth on FCP but I haven't ruled out having another NLE at my disposal along the way. Of particular interest to me are the video scopes in Resolve, as demonstrated by professional colorist Darren Mostyn here...
How to use resolve SCOPES - In-depth with a Pro Colourist - YouTube
 
...I'd wet myself to have that CIE Chromaticity scope in Final Cut! Ha! Truly helps one see where their colors are in relation to the gamuts they shot in and the one's they are targeting for, super useful. Too bad it's only in the paid version of Resolve! Hmm, maybe someone knows of a plugin?

Hi Kye, wow, what an in-depth look into this camera...methinks you're very interested to the point of becoming a future owner?! 😉
I'll reserve my points to "output quality" as each of the internal mechanical aspects and features of the camera will appeal (or not) differently to individual users.
To that end, you've covered quite nicely (and better than I have been able to do) the need for wider dynamic range when shooting outdoor environments...the f/stop range on a typical sunny day is just too much for 8-bit Rec709 to contend with for those of us who need/desire/require that the sum of our frame includes everything from the brightest clouds and specular highlights to the detail and vibrancy going on in the shaded regions. Our eyes capture all of that and I have never been ashamed to ask for and seek out equipment that gets me closer to being able to capture that same natural view. I laugh every time I hear/read someone say that this is niche...no more niche than what I came to expect from my old love, Kodachrome 25! LOL
Getting to understand how HDR and 10-,12- (14-, and 16-) bit imaging can help "get me there" has been a challenge up to now...hard for any of us to realize the benefits of these things when viewed on SDR monitors! Ha! Enter my new M1 Max Macbook Pro with its HDR panel, I've devoted this year to finally educating myself on what is possible (and desirable) with the 10-bit footage I've been accumulating with my S1 for the past few years...in fact, I've decided to hunt down a used Ninja V just so I can become familiar with using 12-bit ProRes RAW at learning what it might and might not be "most practical for" for my style of nature shooting. Clearly, not every situation calls for such bit-depth or, even, DR and learning those lessons through shooting will help educate and inform me as to when varying codec choices are called for...all the more reason for my wanting it all internal to the camera (GH6 and future releases), call up a Custom setting and off one goes, er, shoots, no fuss no muss (f*** external recorders, really, I mean that from the bottom of my heart, Panasonic).
Anyhoo, I thought this article and the accompanying two videos would be of particular interest to you (and to all our fellow folks trying figure out the whens and whys and needs for HDR and high bit-depth)...a two-part interview with Kevin Shaw, CSI and founder of the International Colorist Academy (ICA), where he demonstrates where and how the benefits of HDR acquisition come into play...
Is 2022 the Year You Buy Into HDR? - Frame.io Insider
https://blog.frame.io/2022/01/17/hdr-in-2022/
...a college-level education from someone who knows. 😉
 

I'm excited and looking forward to it! I've been cutting my teeth on FCP but I haven't ruled out having another NLE at my disposal along the way. Of particular interest to me are the video scopes in Resolve, as demonstrated by professional colorist Darren Mostyn here...
How to use resolve SCOPES - In-depth with a Pro Colourist - YouTube
 
...I'd wet myself to have that CIE Chromaticity scope in Final Cut! Ha! Truly helps one see where their colors are in relation to the gamuts they shot in and the one's they are targeting for, super useful. Too bad it's only in the paid version of Resolve! Hmm, maybe someone knows of a plugin?

Once you get spoiled with 12bit Raw files there is no going back LOL. 😬 Once you get the hang of editing them it is pretty easy to do, especially in Studio Resolve.