Do you feel it still focused properly at near minimum focus range compared to maximum? I realize you do a lot of birds, so you felt that the long lenses were just as good on your R tracking a BIF at various distances than native EF body?
Yes they all focused fine near and far. The R tracked very well, the issues are the slide show effect and the slower fps. I have managed many bif shots with it, but it is no 1dx by far. I actually felt like the R tracked a bit better then the 1dx Mark II but it just can't keep up with moving subjects like the 1dx series can. I would never say do not buy it for flight work but if that is your main goal then you may be better off with a 1dx Mark II/ III or maybe the R5 ( to be determined). For the occasional flight work and more still work, I think it is a great camera.
I purposely only took the EOS R to Texas for a birding trip and it did really well