With as common as noises and ticks and such can be with cranks and bottom brackets (in general -- maybe the GXP is less prone to this than other types), I think I would value a known quiet BB/crank combination over replacing it with new parts. I'd even probably favor just replacing the crank rings on your original crank, even though it may cost the same as a new crank. If you can get the old rings off and the new rings on without pulling stuff apart, even better.

Over time, I've learned to not disturb anything that's running right, as simple as the parts or assembly seems to be. I think I'm more sensitive than average to creaks and ticks and noises, and I sometimes beat myself up for changing something that works trying to improve it or otherwise experiment, and end up creating a noise or something that wasn't there before. If your 61k mile bearings are still smooth, and there are no noises, I'd do my best to preserve that.