I have Avid BB5s and their stopping power is quite good. I'm only 210 lbs with myself, Trek 6000, and 15 pounds of stuff I haul with me (don't ask lol), but I've had them work submerged in water while crossing the shallow parts of the Huron River in SW Michigan. So basically yeah - disks kick @$$.

I would NEVER go back to rims. Oh and do they (disks) work in snow - I've yet to know. However, people in the commuting forums who do year round biking to work in snowy regions often swear by disks.

I do use rims on my road bike though (kind of a given...).

I'd suggest getting disks if there will be ANY mud or substantial rain involved in your riding, especially if you are doing downhills or NEED stopping power. Just be wary of front wheel lockup (submerged my stupid face in the river during my crossing when the bike literally slid out from underneath me b/c of how easily the wheels lock up on slippery terrain).


EDIT: avid bb5s I run have 160mm rotors - and they can throw me over the handlebars (165 ish lbs).