The R5c's "color science" remains an unknown at the present time, but for those of us who shoot log gamma or RAW and grade in post, it isn't really an issue. I agree that the rear protrusion might be awkward at first, but it is reminiscent of the Fuji GFX50s that I still own, along with all of the the other GFX cameras (50r, GFX100, GFX100s) and I don't anticipate that it will be problematic. Remember, this not being marketed as a stills camera, and I doubt that it will reach the level of a Swiss Army Knife in terms of its utility, it is first and foremost video camera. And as a video camera it will most likely spend most of its time on a tripod, monopod or other supportive devices.
"If you're gonna always throw it on a tripod, there are better video cameras in my opinion, for much less money." I would be interested to hear about those video cameras.
I was not aware that the firmware update for the R5 has negated the overheating issue. I'm not sure, however, how that could have been accomplished, and if I had to guess I would say that they reset the software time-out for overheating. But overheating is not only a factor of the camera's internal components, it relates as well to atmospheric conditions. And here in S Florida it gets hot, and so does a camera sitting out in the sun.
Anyway, I will reserve my opinion of the R5c until I actually have it in hand and have had a change to put it through its paces. I have no intention of using it as a stills camera, despite its apparent capability, and would relegate that function to the R5, with IBIS.