I have had my Trek 5500 OCLV since 95 and haven't had any problems with it at all. I keep thinking of reasons to buy a new frame but this one has lifetime guarantee on it so I'm going to keep it forever! I replaced the fork with a Reynolds full carbon and that was an improvement. The components are Record BTW which is a dream to ride on. I love my bike.
I work in aerospace as a structures designer and have done some work in the area of carbon design, but not enough to make me an expert. One of the programs that I worked on, now defunct, was a semi-heavy lift rocket, Delta III. I was working on the design, production and installation of the tunnel covers (don't ask), of which some of the components were carbon. Well, on one of our launches we had an anolomy and the rocket had to be destroyed shortly after launch. As many parts were pulled out of the ocean as were feasable. The items were sent back to our facility and lo and behold, one of the composite components, a good sized piece that I had been part of the design team on was in perfect condition. The oygen tank , (aluminum, pricey aluminum) that it was attached to didn't fare nearly as well.
The story doesnt mean anything really, just as an aside of one of my experiences with carbon fiber objects. I haven't worked on any other carbon product since except for Space Shuttle components. Actually, I was involved with the investigation of Columbia's demise. That is a very famous case of carbon failure. But that was a wing leading edge component that was hit by a chunk of foam at very high velocity. Put a big hole in a $1,000,000 component and allowed 3000 degree F plasma to burn up the wing from the inside out. But I digress....
I love carbon!