I agree that the C'dale six would be a more apples to apples comparison. the Giant is a great bike, so in the CAAD. I have a CAAD and love mine. I never rode a TCR, only a Specialized Allez. the C'dale was far superior to that bike.

you should definately ride both since its your dime. Pick the one you like best and feel the best fit on. then buy that bike. I can't think you'll go wrong with either one.