I'm not sure if i'm too late Ross but the Giant Propel is a good bike. Two friends have them and it is very stiff. they have them not for racing but it's a good option if you want one frame and two sets of wheels, training and racing may be the option.
I raced all the time on 50mm full carbon clinchers and they are HARSH as a training wheel. I'd recommend against a carbon rim that mine were as the braking is not good at all. I can't attest to disks but my Ultegra rim brakes with steel hoops stop almost immediately rom 20+mph.