I've got CCB on a Ferrari 458 and a Porsche 911 Turbo S. They have superior stopping power to the brakes on the M5 but that could be a vehicle weight issue. The Porsche has the best brake feel hot or cold of any car I've driven - when dry. The Ferrari's brakes work best with a little heat in them. The Porsche doesn't like being driven through standing water - it takes a split second for the brakes to dry but you have no brakes in that instant.
Both are fine coming out of the car wash - tap them once just like any car.
Bottom line - I wouldn't pay the extra to get them on a big sedan like an M5, and I wouldn't recommend them unless you are tracking the car. I wouldn't have a sports car without them for that fade-free stopping power when driving hard in the mountains.