I have an '09 Pro SL. I also have an '08 Roubaix S-works SL.

I like the Roubaix slightly better for rough roads (comfort), steep (low gear), seated climbs, and long sweeping turns. The Tarmac wins on performance everywhere else.

Sharp turns and maneuvers are easy. The bike is very responsive. I am also more comfortable leaning farther in a turn than on the Roubaix, but on wider, sweeping turns on a descent, I have to actively turn the Tarmac more rather than just shift my hips and weight slightly.

Anything standing is better on the Tarmac, from sprinting to climbing. For some reason, I feel that seated climbs feel more sluggish.

It's very stable descending. Only the wheels change things there. I don't know about durability, yet.