Carbon fiber fork and wheel rims scare me to death, however, to be honest, I have never used either except for a very short while - a Bianchi I bought once had had a carbon fiber fork installed, replacing the original aluminum one. I rode the bike two times with the plastic fork and then swapped it out, going back to the original fork that the bike was issued with.

Why do I fear plastic bikes? I have heard bad things regarding them, bad enough for me to do a search on Carbon Fiber Bicycle Crashes. If that does not turn you off of carbon fiber bikes and components..?

Just guessing about this next comment, but I cannot help but believe that, at one point in time, the Simplex(Dupont Delrin plastic) derailleurs were thought to be the cat's butt. Of course, they were not all that great. In fact, their presence, at times, cracks me up:-(