@Horton. Agreed, and yes, forward pressure is the function of the heel piece pushing the boot forward into the toe piece. I’ve seen and fixed loose boots on Reflex plates.
Do you have any other material on your plate to make sure your boot doesn’t move? If you look at the LaPoints’ plates, or Chelsea Mills’, they use bondo to make a heel cup in which the heel of their boots sit. They don’t rely at all on the nylon centering screws.
And my point wasn’t that your boot would move once in the binding, it was that you might not have your boot in exactly the same place every time you click iin, assuming no centering screws or other product to center your boot. But as noted, with your scores being consistent, you are probably in the same spot all the time. For an interesting experiment, the next time you are having a crappy set, try releasing the binding and resetting your boot before clicking back in. See if your set improves.