mtol

I've gotten used to the focus peaking on the S1 but I find it not as good as the GH5. Color options seem more limited and it doesn't feel as precise.

Yes, I know - I have my G9 setup like that, I use it a lot for wildlife video 🙂

Yes, it looks like they came to the same conclusion that I did....its not feasible for video. Also their implementation of encryption for the sake of speed is very weak. The 64 LFSR encryption method can be reversed in less than an hour with a fast enough modern computer, even they admitted it wasn't very good and had to be downgraded from the typical 256bit standard due to IO speeds and that was in 2014.
Your comparison of 5200RPM drives is mixing apples and oranges, the drive read/write speed is not where you will see the most penalty, typically the encryption/decryption is done in the CPU which is where you could get up to a 30% hit when reading/writing to the encrypted drives. Modern CPUs tend to have way more power than most users need so you wouldn't notice the hit to the CPU unless you did a before and after benchmark and modern CPUs are designed to perform cryptographic functions efficiently. The problem of course as I mentioned earlier, is that cameras do not have all of these spare CPU cycles laying around or onboard TPM chips. In the Magic Lantern example the camera's CPU would be needed to encrypt every byte of data in real time which is where the performance penalty and unreliability would kick in. 
A camera cannot afford to lose 30% of its CPU and encounter up to 20%+ more storage latency when recording video or shooting bursts of images; the buffer would never have a chance to clear.
The true hardware solutions like the USB-C drive I sent you manage to skip this penalty because you are technically writing to a storage space after passing through a dedicated encryption chip whose only purpose is to encrypt the data; data which can then only be read after the proper pin has been input into that dedicated encryption chip. Even though this may still incur a small penalty in IO, you manage to get enough remaining IO to conform to the USB-C standard which means it will have enough remaining IO bandwidth to meet the USB-C data transfer standards.
Quick Google Search
http://cherrybyte.blogspot.com/2012/11/quick-comparison-of-disk-performance.html
https://www.phoronix.com/scan.php?page=article&item=2019-linux-encrypt&num=2
https://www.isumsoft.com/computer/how-much-does-bitlocker-impacts-on-hard-disk-io-performance.html

I am sure it's possible to make a more user-friendly solution than the one I described above, but the safest way to avoid in-field decryption is to make the camera unable to decrypt it. This could be a usable solution as long as it's easy to toggle encryption on and off. Even the people who need encryption will probably not need it for 90+% of their work.
I don't know whether additional hardware is necessary for sufficient encoding speed. I would guess it's necessary for encrypted high quality video, but that encrypted photos at a slower framerates can be done with current hardware?

The camera doesn't need to know the private key. Give the camera a public key the first time you set it up. To view the content, decrypt the material with a private key from the safety of your home on your home computer (or through a cloud based system).
The main hassle would be that you would never be able to review your material from your camera, but neither would the authorities/whoever you are encrypting it from.

There are a few manufacturers of encrypted SD cards, so that would take the onus off the camera to do it but you'd have to do some investigation on the speed implications as they are generally made for things like automotive applications rather than the higher demands of writing 4K 10 bit video files etc.
At the risk of pimping the Toshiba FlashAir SD cards yet again......
These cards do provide a solution in that they can automatically offload files in the background to your phone while you are shooting which then means that you have files that are as secure as your phone is from being accessed, providing you are writing them internally, but then you can use an app to encrypt them if you offload them to the micro SD card.
It can also automatically be FTPing them to a cloud server as an additional backup which circumvents the problem of your physical media being seized whilst its in the camera or on your person.
Having secure physical storage is one thing as it means no one can view your footage but if it is taken off you then neither can you.

It is interesting that the top three spots on Andrew's list of the most popular cameras on EOSHD are all M43 cameras.  Yet every day we have new posts bemoaning the impending death of the format.  And here we are posting on a GH6 "rumors" thread that is 27 pages long and has been active for over a year.
 
It really feels like the death of M43 if it comes, will be due to a self fulfilling prophecy in the minds of its users and not based in any rational assessment of its adoption or the interest of its userbase.  
If Panasonic does decide to abandon a market that they lead and tries to cram the L-mount down our throat it will be one of the silliest decisions a corporation could make.  But I wont try to predict the future as it wouldn't be the first time corporate heads made a bad call.
For the last year or so now Panasonic has been pushing adoption of their new full frame camera line and they probably want to give it as much room to breath and grow as possible.  I think with the new release of the S5, they'll also want to give it some time for new adopters to buy in before they release any news about a GH5 replacement.   At least that is what makes the most sense to me, but I do agree the lack of guidance from them and full support of the format a bit worrisome.  For example, the EVA1 really should have been M43 with maybe a bundled EF adapter or an interchangeable mount-- that alone may have given their user base more confidence in its future.  It is also too bad that the L-mount and M43 have such similar flange distances that an adapter between the two is probably not in the cards.
That said M43 is still my favorite ecosystem and format and none of the full frame cameras have really pulled me away due to some combination of rolling shutter, cropped video, heat issues, or just the size of the bodies and lenses.  The A7S III looks the most promising to me, but I'm still not entirely sold on the need to move to full frame due to weight/size of the lenses and the shallow depth of field that I mostly consider a negative for video.
Anyway, It would be sad to see Panasonic walk away from a mount that arguably has one of the most diverse ecosystems of lenses and adapters on the market.  Hopefully, we'll get some good news soon from Panasonic after they have given the S5 some time to sell through.