Obviously, I still need the 53T ring -- that 53-10 gear will be critical for sprints! A 34-50 gear might be low enough for climbing cliff sides, but a 30-50 would be even better. So I'm sticking with triples.

I'm pretty sure I read that the design of the rear derailleur SRAM requires for that size cassette makes even a two ring setup impossible.

The good news is that this ought to solve the rear wheel dishing problem as those huge cogs will be able to ride above the spokes inside of the drive side hub flange. (Actually, Shimano is already doing that, aren't they?)