Even though I have never ridden one, I am sure the CAAD is a wonderful bike. That being said I think carbon has a better ride quality even in rough roads. It is stiffer but it doesnt mean it's going to break under power. I've heard the CAAD 10 probably rivals the expensive carbon frames but I am just a big lover of carbon. Roads around here in Atlanta get rough as well and my carbon roubaix rides way better than my aluminum felt.
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Cat 6 going on PRO....