How about a little above and beyond regular use by a larger guy?
I range from 220-245lbs and currently have two CF bikes.
The first is a Colango C-50 that I've used on two RAAMs, three 500 mile races, four 1200ks and all the interim training rides (8-10k miles a year since 2005). I also t-boned a van, in 2006, at 35-40mph resulting in a broken wheel, and crank arm but the frame/fork was fine.
My second CF bike is a custom Calfee tandem. I've done two RAAMs and three 500 mile races on it. I don't really know how many training miles.
CF frames are not a problem for most clydes. Wheels are really the only weak link.