Another consideration w/ the Capo is that you will need a new crank. The one that is on there is absolute crap (4 chainring bolts instead of 5). the Felt is probably a better bike, but I like Cannondale as a company much more than Felt and I think the Capo is a great frame. So, I would probably go w/ the Capo + a new crank. Sounds like you have your heart set on aluminum?

All of those bikes are aluminum, is there a reason you don't want steel? I would recommend the Jamis Sputnik if you are open to steel.