The aspect of 10-speed that I like is that of having just two rings up front. One can get that with a nine-speed setup too, of course, and I do run several of my bikes with 22/36/bash. That range covers the trail riding that I do. However, I am wanting a bit more top-end on the mountain bike that I also often ride on pavement, and for that something like the 26/38 setup I can get on a 10-speed crankset seems just the ticket. I'm hoping to make the change this spring before the snow melts. I've got about another month.