Sony FDR AX100

Yes you are right ... and a little wrong. When you go to the menu and change to 4K at 100mbps it ways on the screen that you cannot capture stills when in that mode. When the video mode is set in the lower bit rate pushing the top photo button will take a photo. When in 100 mbps the top photo button will not work.

Yes it does appear that by hitting the back video/photo button will drop it into a photo mode and then the top photo button works. Of course then videos will not work until going back to the video mode. In HD or 4K 60 mbps when recording video with the video button as well as taking photos with the photo button work together. The menu when going to 4K 100 mbps still says photos are not capable in that mode.

Thanks for the clarification, I did not realize the selector on the back allowed what the menu says is not possible. I learned a new capability. Thanks.

Anyone besides me find the actual quality between the 60 and the 100 mb/s no different? Granted I have not done a test in a while, as I only test when curious, but when I did tests, and pixel peeped at 200-800% with and without high detail and motion, I could not tell, except for larger files. So just curious if anyone else bothered to check or is the thought what counts?

Mizamook, at some few older 60mbs shots i discovered a strange pixelation which maybe will be better with 100mbs. Usually i also see no difference, but i don't care for it and shoot with 100mbs.
There are 2 scenarios if you will try to check it again. I think your location is perfect for these.

scene 1: Overhead shot (low angle) between trees with some sky between the leaves or branches while turning your body up to 360°
scene 2: Handheld panning at mountains or else while the lower half of the screen is high detailed with structures and distances (high and deep) and the upper half of the screen is relative flat with only some bright clouds.

Maybe by this tests you'll see a difference.