I bet you are right, that I may be reacting to the geometry more than the frame material on the comparison between the Santana and the Co-Motion. The Carrera is an excellent tandem! I have not looked at the Scandium. Do you know if the frame geometry is the same as the Ti-700?

Actually the bike I rode was Jack's demo bike at Tandems Ltd. On the day I was in Birmingham another nice couple from Huntsville was there. They ended up purchasing Jack's demo Ti-700. Jack is a wealth of information on Tandems I learned a lot from him during my visit. He and his wife Susan are great to work with.