Originally Posted by Velo Dog
Is there any reason other than the coolness factor to use discs?
If you're a fair-weather cyclist, a weight-weenie, or a retro grouch, no.
But see, Daven, the OP, lives in Merry Olde. Perhaps you've heard, it rains a lot there. He commutes by bike in the rain.
I live in the Northeast US. We get snow. Lots of it here on the shores of Lake Ontario. Maybe you've seen that on CNN or The Hyperbole Channel™. I commute by bike in the snow. See that white stuff on the ground behind me in my avatar? Snow.
I can't speak for Daven, but here's my experience.
My first winter bike had V-brakes. Through the winter I had to replace the pads every couple of weeks. They don't last long in the wet. The wet also causes grit to stick to the rims. It turns to grinding paste. By spring, I had worn the braking surface of the rims concave. This is an unsafe condition. Since then, I've seen other rims that have exploded due to worn braking surfaces. This convinced me that rim brakes are not the right tool for the job. And it's damned expensive replacing brake pads every couple of weeks, and rims every spring.
My current all-seasons, all-conditions commuter has Avid BB7s. In three years of 52-week riding, I'm only on the fourth set of pads. I haven't had to replace rotors (or rims) due to brake wear or damage. The brakes have not clogged with ice and snow like my V-brakes did. They also stop exactly the same in the dry, the wet, and the snow. I don't have to compensate for wet or dirty rims. They just work the same, stop after stop, every single time.
I won't ever own an all-seasons, all-conditions bike without disc brakes. IMHO, disc brakes are one of the defining characteristics of an all-seasons, all-conditions bike, right up there with lights, full-fenders, mudflaps, and room for studded snow tires. (All of which also do nothing but add weight if you're a fair-weather cyclist or weight weenie.)
I don't think they're necessary on a fair-weather bike. All my fair-weather bikes--including my weight-weenie bike--have ordinary road calipers. They stop just fine.