Honestly, I can not tell a difference between my 10' S-Works Roubaix and my 2009 Roubaix Comp (also carbon fiber, but based on their last generation of Roubaix design.)

Before I bought those Roubaix, i had a CAAD 10, CAAD 9, Giant Defy Composite and a Giant TCX, the CAAD 10/9/TCX are super stiff, fast, but too harsh on the road, the Defy Composite had a weird geometry and not as smooth as the Roubaix at absorbing road vibrations (However I did ride a 100mile century on the Defy Composite wearing no padded shorts so it's comfortable enough to handle long distance)

Hope it helps.