I've found that riding a few crits each year can be way, way harder on a cf bike than many years of commuting. I commute on 3 carbon fiber bikes. My "A commuter" is a 2007 carpe diem and has 20K+ of year round commuting in the wet pacific northwest. The only problem I've had is fender rub (more of a problem with crabon than metal). Make sure to tape up the frame and/or buy skinny fenders.