Have you tried a torque wrench?
I just went out and bought a torque wrench from my LBS to try and solve this exact issue on my Roubaix. I set the wrench to less than the torque recommended by Specialized (45 in-lbs) and began tightening. I did not get to the torque when the head of the bolt snapped right off! There was no damage to the post, frame, collar or the dingle-hopper the bolt threaded into. Just took it back to my LBS and they replaced the bolt. Obviously it was a good thing the bolt failed before the collar/frame/post. I've checked the torque wrench against several other calibrated wrenches and it is within 5% of the expected settings. You think the seat collar bolt is robust enough to hold the specified torque? I have not tried again as I now know you can give the collar bolt a good twist without causing damage. Has anyone else tried to tighten the collar to specification?