So.... I'm rethinking the RF 100-500mm, and considering the EF 100-400mm II and an EF 1.4x. Why? Because it would ALSO work on the 7D2.

As I mentioned above, I already find the 70-300L's reach limiting, and it's equal to a 480mm FOV on the 7D2. The so 100-500mm buy me the same reach with the R8's higher quality pixels. Maybe some extra cropping power, but no real extra reach. The RF 1.4x would get some extra reach, but currently only works on 3 lenses, the 100-500mm being the only one I'm interested in (the other f/11 super-teles all appear soft in Bryan's charts... maybe they're better real world).

The 100-400mm on the other hand would buy me more reach on the 7D2. The extender would nearly double my current reach (560mm vs 300mm)... but yes, bit softer. The lens would also work on the R8 w/ or w/out the extender w/ the EF adapter, which I'd most likely be getting anyway to keep my other lenses available.

A worthwhile option, or a pointless clinging to my old camera where I'd wish I'd just gone with the RF from the start?