The Choice of the New Version II of Canon Super-Tele-Lenses EF500mm f/4L vs EF600mm?

[Vern]

Ok, here's a shot with the combo:

EOS 1D X, EF 600mm f/4L IS II USM + EF 2x III Extender, 1/320 s, f/8, ISO 4000

Here's a 100% crop of the above:

Thanks for sharing. That looks encouraging - fairly smooth noise in the 100% too at ISO 4000. Maybe I do need to 1DX. I think I'll set the 600 up next w/e w the 2XIII and see what I think - will have to struggle to focus, but I'm curious now. Hope to see some more samples!