Yeah, the walls on the CAAD 9 are pretty thin, and the seat stays are supposedly lighter than carbon seatstays. As far as durability goes, I'm not sure. A CAAD 8 would be more comfortable than a CAAD 9, but if the Orbea is more upright, then it'd be more comfortable than both.

A crash that'd ruin a CAAD 8/9 would probably ruin a carbon bike too though. You might want to check out some of the specialized Tarmacs and Roubaix models, as well as some of the higher end fujis. Those bikes are more comfortable than the CAAD series, and are plenty fast.