... I have the Avid Mech Discs, and they have very impressive stopping power for that price. I also have Shimano Deores...they feel great and are very low maintenance! I don't think u would be going wrong w/ either one, but the Deores may feel a bit better.
I have the hayes HFX9 and they've been good to me so far BUT have been a bit finicky when it comes to rubbing. Never tried the avid's but they seem to be real good as far as mechanical brakes go.
I have the avids. They're noticeably better than rim brakes but I'm not completely satisfied with 'em. I think the brake on the front wheel helps a lot but the back wheel just makes it easier to skid (not a good thing). They seem a lot louder too when you go through water or mud, or if you dont have 'em adjusted perfectly. I would recommend them over v-brakes, but I haven't tried any other disc brakes so can't help you there....good price though.
Go for the Hayes :-$ !! The Hayes Comps are actually better than the nines that they have out now. Although the Avids are good brakes, the Hayes will give you better modulation and increased stopping power. After switching from mechanical to hydraulic, I can't see myself ever going back. Unless I become a full on XC rider, which I don't see happenning. No offense to any XCers, as I still ride XC once a week or so.
