I made literally the same choice just two months ago. Chose the S2 over the CAAD and I love the S2. Super stiff and fast.
Not knocking the CAAD, but I definitely don't regret the decision.

I built it with Force and Soul S2.0 - 15.2 pounds.

Here's a pic with my Soul C5.0s. I also switched the bottle cages to Vincero magnetic.


Untitled by inertianinja, on Flickr