If you're trying to find reasons to implement R7 (or, for some/one of you - R6!) then check out
these pretty graphs, which show some of the performance benefits of R7 over R6. As with all statistics they're totally meaningless, but you might find some maths obsessed manager who falls for it.
(Don't get me wrong here, my R7 server actually *feels* a shitload faster, but I could be dreaming that - I just have no respect for statistics)