With all external cup systems, the cranksets are the same, and differences between english & italian are taken up with the cups.
I also have a BB30 Cannondale with the campy adapter cups. works fine.
As for frame material - yours is one of the commonest questions out there. the most sensible answer is that ride is much more to do with the frame design, and less to do with material used. my favorite bike (and I have them in steel, alloy, carbon and ti), is my updated '95 Merckx Litespeed.
Ti is generally considered similar to steel but without some of the drawbacks like corrosion.
One of my stiffest bikes is a steel Coppi. And even some carbon frames have a reputation for harshness.
Another comfortable frame for me is an older Fuji - all alloy with carbon fork.
Alloy like an older Cannondale can be very stiff, or quite comfortable like a Merckx SC.
sometimes you just don't know until you try.