We've done a fair amount of side by side testing of H264/265 and ProRes. Here are the highlights.|
1. H264/h265 appear at this point to be largely identical. Even under extreme stress testing (heavy grading) we see no difference between the two. Haven't tested H265 since the firmware upgrade, so there may be some differences.
2) H264/h265 are both excellent codecs, far superior to previous DJI low bit rate codecs. The take grading very well, and many people will find them to be all that they need. The one drawback to these codecs is that they undergo quite a bit of noise reduction (smearing) and output sharpening, (aliasing) even when set at the lowest levels available in Go4 app. This is to be expected, but is the primary difference you will see in comparison to ProRes. Some people prefer the over sharpened look of the h264/5, but as a professional, ProRes gives you the ability to sharpen in a more granular way in post, giving you slightly more delicate detail, and a minimum of sharpening artifacts.
3) ProRes will have slightly more noise, but it is generally fine and reminiscent of film grain. It handles highlights better in D-Log than H264 (which currently has a slight error in the encoding of d-log), and in theory will accept more adjustment in post than the H264/5. (So far I'm pretty impressed with how well the H codecs grade, but proRes should, again in theory be even better -- in my tests so far, I really haven't seen the H264 codec "break" or band with extreme grades, in the new firmware, so it's hard to absolutely say that ProRes excels here, except in theory). Currently ProRes is limited to D-Log and standard profiles, and doesn't have M4/3 lens corrections applied, which is problematic on the wider lenses including DJI's stock lens, so it could be considered limited for now.
4) RAW is really not a video codec and so it's main highlight is it's ability to be handled like a RAW photo in photoshop, This results in the post process being much more time consuming and also much more controllable. Image quality in Raw is not necessarily better than proRes, but you can apply much more extreme adjustments to the imagery. There is currently a lens correction error with RAW involving the 25mm lens, that leads to uncorrectable Chromatic Aberrations. This will hopefully be corrected (by Adobe) soon.