I would tend to agree with Drakulie. I actually performed one test where I placed the clamps about a 1/4 inch from the frame on one racket when possible and an inch or more away another racket (same make and model and grip size) and the racket which had the clamps placed closer to the frame had a tighter string bed. This was done on a Prince Neos though. I think there would be less of a difference a Constant Pull machine.
Another point which probably is obvious to most people is that if you place the clamp right up against the frame you will not be able to recover all of the drawback on the next pull. Anyone agree with that?