While this is now the outgoing generation of the XTR crankset, they still are one of the best XC cranksets around. While everyone is going to a single ring setup, I still prefer having two rings (and somedays still miss having a triple ring setup because of the 46T outer ring).
These cranks are stiff, solid, and flat out just work. They may not be fancy and made from carbon but they can take a beating and keep on going. I've got a set that have survived three different frames over the past two years and they are still going strong.
The chainrings do wear out but with two rings the wear will be higher than running three rings. If you have massive legs and a VO2 like sled dog go for the 42/30 ring setup.