Although I own an Ultimate and really enjoy the ride and styling of the frame, I guess the consensus is that the carbon rear stay really didn't do much for the frame except for marketing appeal. In theory the Ultimate might be less durable due to having multiple joints made from dissimilar materials (Ti to Carbon) which might fail later vs the all Ti Tuscany. The Tuscany is known for being an all-around enjoyable fast, touring bike and the Ultimate is a more stiffer racing frame. Personally I chose the Ultimate over the Tuscany (after riding both for about an hour) because I felt the Ultimate was more responsive and had better styling. Let's us know which way you go.