I have been using back-button focusing for so long its hard to imaging an alternative, but it does result in a brief delay to first acquire focus and THEN hit the shutter button. I have set up the camera as I saw in some of the early videos, with the back * button set to eye-tracking and it works very well, with a bunch of contiguous focus points dancing around on FG elements that were close to the plane of focus, and then finding an eye if there is one.
But some subjects will have bugged out in the meantime. I have seen references to people using the old shutter-button focus but with the new eye-detect. I’ve tried it, with the shutter button set back to focus and the focus mode on eye detect, but if there is any detail in the BG the focus will jump to that detail. It is very different behavior than I get with back button focus.
I’m feeling stupid, but what am I missing? It seems the two should behave the same.