Quoted from Atomicboy:
I would be worried about non-cc'd/DP Pf's lifting paint after one of these were on for years.
If you're thinking that the paint would adhere to the poly, waxing the pf before would likely help (or completely) prevent this. Since the protector isn't moving, and the motion of the ball over it won't transfer to the pf (like it does with thinner mylar) the layer of wax would seem to prevent the direct contact between the poly sheet and the paint. A good layer of wax may well also create a seal between the pf and the poly to prevent the intrusion of dirty between the poly and the pf. But if there was some intrusion, it likely wouldn't have the same effect as with dirt getting under loose mylar because of the lack of movement of the poly sheet or transfer of motion from the ball thru to the pf/dirt.