I have had 2 games in which I installed these protectors, (old thicker style) RFM and Paragon. Game play seemed more affected on Paragon, probably because it was more noticeable because it is slower. The biggest thing I noticed is there is some sort of different "feel" to the ball as it moves across the playfield. The ball is a bit quieter as well.
I think it is a great product. There is no wear at all on the playfield after installation. It does play a little different, but not in a bad way, just different.