I think durability on each would be about the same. It depends on who you talk to, as some think Carbon has a higher potential failure rate if compromised (crashed), and damaged structurally where you can't really SEE it's damaged. Carbon Fiber gains it's strength by the weave of the material and if damaged it looses integrity pretty drastically. Alu or Steel will bend/flex before it fails, carbon is incredibility strong and stiff, but once it reaches it's breaking point, it breaks.

The main thing about the carbon is it absorbs a lot more of the vibrations, etc from the road/path, which means less going into your hands/arms.

Shannon