I have disc brakes on my mtb and really appreciate them in city riding. I can stop on a dime. My 'cross usually skids to a stop, and sometimes never a complete stop and I have to put a foot down if I really need to stop (at stop signs, etc.). Part of this might be the brake pads? I'm not certain, but do know that I feel so much more secure riding with disc brakes. Lemond, for one, makes a cross model with discs. A negative point is that they are heavier than cantilever brakes, and might not be legal in some races. I don't know how they compare in terms of getting clogged with mud. It's never that muddy here....oh, but it is wet due to the fog sometimes. The cantilevers will slip in moist conditions and the discs will still work well.