The latest firmware update for the R6 (1.5.0) sure is making a difference. I find the Eye-AF/tracking to be considerably better than before. It now finds a bird without hesitation, even, and this is a big change, when the bird is quite a distance away and even in low light.
After updating the firmware I tested it out on the birds that fly by my house, gulls mostly, some magpies, crows, etc. and the difference is very noticeable. The Eye-AF now finds the bird quick and doesn't stray the way it used to. It's as if the Eye-AF is glued to the bird.
One thing the Eye-AF/tracking was also bad at was big birds, close by. At the close of every day a resident Grey Heron sweeps in from up high and sits on one of the houseboats in the canal, right where my apartment is. The R6 had serious problems finding the eye of the bird as it came down. I had the impression that the bird was too big and the camera sort of lost the big picture and instead of on the eye it would focus on light coloured patches, like on the heron's shoulders. So I had to switch to spot AF to get sharp, in focus shots. But no more. Today I waited for the heron and sure enough, in he came, diving down. It was close to sundown, very low light. But the Eye-AF found the eye immediately and stayed there as I tracked him. I took a burst of 35 shots, a sequence starting as he came down to landing on the houseboat below me. Only two were so-so, all the rest were in focus. This is a big improvement. Here's one of the Heron shots. Minimal editing. Cropped slightly for reasons of composition, added some light, resized and ran it through Topaz Denoise.
forum: Canon EOS Digital Cameras
I missed it before, Levina your detailed description makes me want to buy this camera