My brother has a Bachetta Corsa. I used to ride a CA2, but sold it after I bought the S40. I really enjoy my S40. It's all stock, except the bottle cages. That means I have a single gear up front. I live in Parker, CO. An "easy" ride is 600 vertical feet. I frequently climb 1,000 to 2,000 feet on 25 to 40-mile rides. I've also done mountain passes.
The S40 is a much better climber than the CA2. I prefer the lower feet position vs. the CA2. I'm now very comfortable racing down hills on my S40. But it's hard to beat the carbon fiber stick frame and long wheel base of the CA2 for big mountain downhills on rough Colorado roads. That's one thing I miss.
Oh, another thing. The shorter wheel base of the S40 is much better for maneuvering, especially tight turns.