Anyone interested I also tested the EF 400mm III vs the RF 400 in the AF department and did not notice any difference between them. However they do both focus faster on the R3 vs the R5. Nothing scientific just actual use and nothing notable.
Another point is if you use the R3 in full silent mode the shutter close feature does not work and is grayed out. If you turn the silent feature off it closes like the R5. This is strange seeing the R5 only has full silent and it closes. Hopefully this is addressed in a firmware.








