I have not ridden a carbon frame, but they say they are more comfortable than AL...as it absorbs the bumbs better. I have the AL Defy 1 and do not have a problem with comfort at all. If money is not a problem, get the carbon. But if you are on a budget, you will be VERY happy with the AL frame. DO NOT buy the Advanced because someone tells you carbon "performs" better. The Advanced 3 weighs about the same, has the same components and WILL NOT make you go any faster than the Defy 1. If I wasn't on a budget I'd go for the Advanced for the comfort factor. Both bikes will make you happy.