I don't ride cannondales currently, but I did ride them for years. The first one I had was the Black Lightning which was for a long time the stiffest bike that Bicycling Magazine ever measured. The ride was a bit harsh but the handling was superb. Also, I felt the stiffness was a big asset for me because I am large and strong. Big, strong riders do well on stiff bikes. I was able to ride this bike on century plus distances without any trouble.
The new aluminum cannondales have much more compliant rides but I don't think they handle quite as well.
Also, according to what I have read, the difference between the various frame materials is making less and less of a difference because the engineers are learning how to compensate for the characteristics of each material.
If you can, test ride a variety of bikes and get what pleases you.