Quite a few pros go with full aluminum, actually. For example, someone such as Danilo di Luca, ProTour champion, who can ride just about any Bianchi bike he wants, chose to ride an ALL ALUMINUM FG Lite frame.
Shown here:
http://bianchiusa.com/
Why? Because aluminum CAN be made to be forgiving, but still make you feel like you've been shot out of a cannon when you put the power down.
My current bike is a CAAD8 R1000. I'm 5'7" and 140, and ride a 50cm frame; i.e not a lot of weight to smooth out the bumps, and a VERY stiff frame. AND I LOVE IT.