I am really interested in this topic, since I recently changed my second bike from a no-name brand Chinese carbon to a Cervelo S1 frame. I was disappointed at first, probably the extra weight and loss of comfort. Then however it seems to save your legs up for the second part of the ride which I thought quite interesting. The carbon would somehow go dead in the last part in a ride, where the S1 seems to make it easier to turn the last couple of slight uphills into the wind into enjoyable pain. It was as though the carbon strugglled to punch through the wind. I have a 38 mm carbon Yishun set of wheels on at the moment which I use all the time, they seem to be solid. I did try a set of Easton EA 90 SL's for a while , but am also disappointed in them. Have never had them on the S1 though. I am wondering if the 38 mm carbons are the best thing on the S1 though. Would like to know what everybody else thinks, I feel it is overrated , but like the way it looks and the way it makes you stronger if you use it as a training bike. Not sure if it will become my first choice bike though.
