I cannot speak for Geoff but I got a pretty simple workflow. Adobe Premiere Pro CC 2015 supports HEVC however the performance just is not there yet because my GPU lacks HEVC hardware support so I interchange with the old workflow a lot.
Basically its: Shoot Video -> Convert Video -> Edit Video -> Export DNxHR 1440p25
Whereas if I just edit the footage and no colour grading I do not convert the footage and just: Shoot Video -> Edit Video -> Export DNxHR 1440p25
Personally I never convert the 4k footage to the 1080p before edit because its too much hassle for me, but I found 2160p to be vastly useless regarding my export so I always export to a 1440p master file and then I use that master file to create smaller versions like 1080p with lower bitrate etc for my clients, for my YT I only do 1440p because 2160p is a niche at the moment and requires quite fast internet speeds it also creates huge file sizes and at the moment Blu Ray discs which I use for archiving are VERY costly for 50GB and 100GB, if I can slap the entire project on just a few 25GB discs I am happy, but a pack of 10 x 50GB are same price as a pack of 50 x 25GB BD discs.
If I convert the HEVC to ProRes422LT I use the LUT, if I edit the HEVC straight in Premiere Pro I also apply the GammaDR2LOG from EOSHD this is only if I use the GammaDR profile but seeing how good colours the camera shoots with the various Picture Profiles, I am actually moving more away from GammaDR and just using the in-camera colours.
The reason why people grade a lot of their footage from their DSLR and mirrorless is to get away from that digital look that is infamous today, but the NX1 shoots such good rec709 colours that I think you probably only need GammaDR if you need to acquire colours that are vastly different from the in-camera ones or if the client requests it.
There are various programs to convert the HEVC footage with, you probably heard of them like RockyMountain Movie Converter 2.00.0 and ClipToolz Convert V2, for Mac there are others that I do not know about because I use Windows.
Because Windows does not support ProRes out the box I use DNxHD or DNxHR. I never export 2160p for personal use or family videos only if the client wants it otherwise I use 1440p which saves a lot of space and allows me to still crop in post if needed, I can crop 2 times in 1440p which is quite good.
Because I use Adobe Premiere Pro CC 2015 I do all my grading work in Adobe SpeedGrade CC 2015 but I am also experimenting with just creating LUT's in Photoshop or SpeedGrade from still images and then use them in Premiere with the Lumetri tool which allows me to adjust brightness, contrast and all the good stuff very easily without having to open SpeedGrade or After Effects (SpeedGrade sucks for HEVC editing, better avoid it at all costs until Adobe fixes the performance issue)
