Get the 105; if you get "a little rough", you'll find out that you're NO LONGER ON A MOUNTAIN BIKE!
Sounds to me like you're setting up for utility; that means you have to be "a little nicer" to your steed. When you spec a bike, you do it with one of two points of view:
1.) targeting the type of riding you'll be doing;
2.) building to your limits.
Since you're dealing with overall groups, you have less leeway about your parts; so pick one, and align your riding style to it. (I would never ride the way I do now on a roadie OR a cross bike!)
Last edited by ATAC49er; 05-31-08 at 06:51 PM.