I've ridden the Crossmax's and they are fantabulous. If I were to get back into XC I'd have a set bolted to my bike. The low spoke count of the XTR scare me. Plus, I've always been a big fan of Mavic products. When I build wheels using Mavic rims, it's always easier. Seems the rims are straighter and true from the factory. Not the case with other manuf.
I've not test ridden the XTR's, nor any other Shimano wheelset, but had to true one. What a hassle, the spoke lacing requires a completely different technique. Innovation? I disagree. Changes for the sake of change is not innovation. But I digress.
I've heard about the noise issue with Shimano wheelsets, but haven't experienced it.
Personally, I'd get the CrossMax's.
L8R
__________________
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, "WOW, What a Ride!" - unknown
"Your Bike Sucks" - Sky Yaeger