I also have an 06 Eros Donna and love it completely. It is great for long rides, hills, whatever you need it to do. The steel gives it a smooth ride. Most bike makers will tell you that a good bike can be made from any of the major materials, so there's nothing magic about carbon. I'm guessing the other Bianchi owners on here will agree with all this. Go with the bike that feels good and fits well---I think the idea that somehow a carbon frame will "smooth out the road" better on long rides and somehow result in less fatigue is maybe a little on the mythical/marketing propaganda side.