Hi 223,
He had a .308 before and feels more confident with that rather than the .243, I suppose he feels he went backwards getting the .243, less energy I suppose, I have a .308 myself and find it does everything I want, I don't really think there would be much more carcase damage, it's all down to bullet placement, yes in a roe perhaps, but not so much in a red.
As for the 30-06 it may be a bit over the top, I Googled American sights, and what I found was they use them for Elk, and to a lesser extent for Moose with careful bullet placement, they can fire a heavier bullet but have almost