I have done the Cervelo test ride program twice. I rode the S2 the first time. It was my first long distance ride on an all carbon bike. I liked it, but the saddle was unbelievably uncomfortable, and I was not able to do the full metric century. I cut the ride off at 54 miles.
The week I rode a RS. The course was about 90% chip seal, and the frame simply ate the vibration for lunch. It climbed well, descended better, and carved the turns well. It is not explosive off the line, but accelerates nicely. After a metric century, I decided that this is to be my next bike. It is much larger than my current Allez. I am riding a 56.5cm Specialized, and the Cervelo is a 61. I thought the frame would be a bit big, but it is not. It stretched me out a bit more, and I absolutely loved it.