JayC,
I saw your post on the group buy thread. It was never clear to me whether the clamp faces are in contact with each other eliminating additional clamping force no matter how much torque is applied to the clamp screw. If the faces are in contact, the frame and/or the clamp are defective. I bought a Pedal Force RS on the group buy in 2006. The first time I installed the FD (Shimano FD-6300, Ultegra) I did not prep it and was quite concerned about the torque applied to the screw as I feared cracking the frame. It slipped on the first ride. To correct, I took it off the frame and roughened the inside diameter of the clamp with some emery cloth. I also reviewed Shimano's technical document for the screw torque spec. The document I had did not have a reference to carbon frames. It indicated 44-60 in-lbs. for torque. The present document does indicate one should consult the frame manufacturer for tightening torque. I ended up with about 35 in-lbs of torque on the screw. The increased torque and the roughening of the clamp ID solved the problem. I have ridden over 2,000 miles with no problems. You could also roughen the clear coat on the frame slightly. I did not do so because I did not want to change the cosmetics of the seat tube. Unless the clamp faces are bottomed on each other, I believe this will solve your problem.