I've not compared the cropping element of it yet. I have found that it yields fantastic detail from huge crops though.
For me, the silent shooting side is key, as my 1DX is simply too noisy to use with sensitive subjects, and having heard the mark 2 and 3 on "silent" mode, there's not a great deal of improvement. To be able to shoot at 20fps for otters and owls will be fabulous.
The AF is remarkable, but I'm sure Sony users have been enjoying the same tech for some time.
When I photograph the little owls, getting images of them in focus as they scuttle across the barn roof is difficult. With my 1DX and 7d2 I might get 2 or 3 shots out of a burst of 20. The R5 is sometimes getting 20 sharp shots from such a sequence.
Also, to get flight shots of the owls, because they're so quick, I would pre-focus the camera on a marker mid-way through the flight line, and burst shots off when the owl flew, hoping it would fly through the right area.
The R5 can track the owl from where it takes off, through to landing, tracking the eye or failing that, the head area instead. I can't wait to try it on jumping squirrels when I'm next up in the Highlands.
It's not perfect, and does focus on other parts of the bird at times, but my hit rate has gone through the roof using the R5.
Not sure if people on here know these guys, but Oliver Wright (macro stacking specialist), Chas Moonie and Dave Soons are all using the R5, and getting stunning results. Worth looking at what they're achieving.