So, it looks like I am a B-Raw convert, probably at Q5 (constant quality) compression.
In C4k on the GH5s, it is drawing as needed it can range between in compression for the same or slightly larger files than 1080p ProRes 422 HQ at 27 MB/s ranging from 21-58 MB/s.
That is a manageable file size with the added benefit on the GH5s, of uncrossed C4k, so cropping etc are possible.
Some reviewers, rare unfortunately because constant quality is harder to quantify, consistently state that the file sizes are small overall, large only as needed and plenty good enough for most uses. Constant quality is better than constant bit rate 8:1 (15:1 to 6:1 (as required), but vastly smaller than 5:1 compression at a flat 20 mb/s.
The flexibility of the files in processing is really very good, especially in the highlights and white balance. I do not get the full B-Raw benefits in processing, but the file flexibility is there and what is missing from the RAW options is available from normal processing.
My wife in home improvement mode, standing up in the name of research. This footage was compared to some ProRes and the difference in quality of fine details and post processing was huge. The file size was about 40% larger (the files were the same size, but the ProRes was longer by about 40%). GH5s, BMVA, Hope 25mm, Smallrig 60w into a reflector, exposed for the lit side of her face (green with false colour) and white balance, I most admit was neglected (3800 by mistake) and fixed with little trouble (the light was set to 5600). The skin tones were better than the ProRes, that did not handle the WB error well.
Pans are smooth, colours natural and the exports are much closer to what I see on the screen and the pans are the smoothest I have managed so far. Little or no “judder”.
There is still room for anything from Standrad, Flat and Natural Rec709 modes, some V-Log and ProRes, but to my eye and for my needs, B-Raw Q5 is it. I may need to get another 12G for matching cams, a 3G out as it lacks RAW and I will also probably upgrade the S5II as B-Raw support for that one seem to be very good.
Another change and one that may be even more exciting is adopting false colours.
Seriously folks, it took a New York second to learn and works intuitively. To nut-shell it, green-greys are middle grey (green=skin tones) or there-abouts, blues are under, yellow-reds are over. In RAW you are well in the ball-park. Unlike true colours, they are simplified and consistent. You can expose to taste and by eye, something I struggle with using histograms or even wave forms.
So, B-Raw flogs V-Log for safety and versatility as well as being easier to “eye-ball” with exposure and white balance. Also colours are easier to use than other forms of exposure control.
These two changes fix most of my issues.