Originally Posted by
Kimmo
+1. Stems need to be strong in every direction, so you're just paying for 'black aluminium' with no weight benefit.
IME, carbon bars (particularly aero) do a great job of damping vibration on their own; I'd say if a stem is soft enough to contribute in that way, it'll be a power-sapping noodle, judging from my experience with light ally stems.
Carbon is a better damping material then aluminum. All the carbon stems I have are very rigid. On the other hand, the difference is rather small and my Thomson stem, which is very rigid cost less than half of the carbon stem that replaced it. Carbon stems are not the best bang for your buck.