I'm in the market, as it were, for a new bike. I've been riding my full suspension MTB to work (13 mi RT) since spring and I'm ready to save it for the dirt and get a 2nd bike.

I'm up around 230 and I have a decent downhill that I hit at over 40 on my low geared MTB, knobby tires at 45 psi. There is a couple of stop-lights on the hill that sometimes get me hitting the disc brakes hard - and they work great.

I live in So-Cal so rain is rare, but I'd like to be able to ride in it once in a while when I have to.

Regarding disc brakes, I'm picking up conflicting views. Any LBS tells me I need them or I don't need them, depending on the bike they are trying to sell me. It appears the Specialized Sirrus no longer has the disc brakes on the 2007. The Trek 7.5 FX has a version with them, but the higher end FX bikes (7.6/7.7 don't have them. I was told they are heavy and the hydraulic ones on my MTB are much better than the mechanical ones on these road/urban bikes.

At this point, I don't know if I really need them or not. I guess if I do get them, I can easily upgrade them to a better disc without getting new forks if they are "that bad". If I don't get them, I'm worried about being able to stop down that hill or in the rain. Also, some of the roads I get on are a bit rough, and I'm worried about keeping my wheels true (I ride pretty hard) and then the brakes will be less effective.

Are these mechanical brakes any better than standard brakes?

I'd like to get some opinions on this as I ponder my bike choice.