That is indeed awesome findings! This would absolutely mirror my frustrations with it in low light wedding shooting with the 70-200mm f/2.8 IS II. When the light gets low enough it was struggling to lock on at all. Or not reliably. And of course it struggles with the RF or EF 85mm f/1.2 hitting perfect eye focus, focusing instead on the eye lashes or on the wrinkles around it. Any of my 1-series hits the focus much more reliably.

This is kinda exciting that the AF is finally getting close to 1-series level accuracy. Makes me really excited to see how amazing the R1 AF system will perform. I'm getting an itchy buy it now finger. LOL.