- Ring USM is still faster than STM. STM is just for smoother & quieter focusing, not speed.
- I can't be sure due to the video quality, but it appears there is still some sort of CDAF-style "focus racking" (albeit minor), most apparent in the 1st & 3rd vids. It doesn't "snap" into focus like one would expect from PDAF.
- Not sure how the continuous AF tracking was set up for the 4th vid (or if it was even set up correctly at all), but it clearly showed that that particular L USM lens+body combo couldn't follow the hand as it moved backward & forward from the initial point of focus lock. I hope that's the worst case scenario already (too fast movement), and the firmware is still not yet finalized.
Overall, still pretty fast compared to existing solutions.