OK, I read through all (most!) of this thread, and I don't think I saw an answer to this. I'm looking at the Speciazed Rockhopper and the Trek 4500, both 2005 models and neither with disc brakes.

But there's the rub: disc brakes. Last winter i discovered rim brakes can really suck in the snow and freezing rain. So I'd love to have at least a disc brake on the front wheel.

Question: Can I upgrade the front brake on those two bikes later? What would that entail changing, and about how much would that cost?

(By the way, I do have to applaud everyone for not letting this big thread get sucked down into some useless flamewar, which is kind of what I expected before reading it. . .)