What is the durability on these wheels? I have heard in other circles that carbon fiber wheels have a shorter life span than forged/cast wheels.
The Rotobox wheels do have a very good reputation, and I would say durability wise it would be almost as good as any alloy wheel. They might not last 50 years sitting on a field, but I would be confident enough to say if you don't physically damage them yourself, they will outlast your bike.
We've all seen those broken BST carbon wheels, but I have yet to see a broken Rotobox wheel. Does this mean BST's aren't good? Not really, BST has been around for a long time, Rotobox is a fairly new company. Rotobox does make hell of a composite wheel.
That being said, I can show you many pictures of broken OZ, Marchesini, OEM, Forged wheels as well. I've personally bent OEM wheel simply running over an apex at a track.
I know a handful of people running Rotobox's on track and never heard anything negative from them either.