You will notice a difference in braking power. I have a great v-brake setup (xtr on ceramic rims) on one bike and Avid mechanicals on another. Huge difference. Less fade, stonger brake, just better all around with the discs. I've always been an xc guy and thought discs where just for the gravity guys, then I actually rode discs and from this day forward any mtb I get will have disc brakes. Better brakes make a faster rider.