My only thought with Cliff's shooter lane setups is then you have the balls hitting hard against the sharp edges of the metal protectors... and with multiballs, etc it's throwing the balls against it quite a bit. In fact the long piece that is on the bubble side seems like it will skid along the edge of every ball as it is launched. I just wonder if that will scratch up the balls prematurely and then they scuff up the rest of the PF?
Probably not an issue as he's been selling them for years and never read a complaint... you could also replace the balls earlier (if you regularly inspect them).
I gotta say I've never seen shooter lanes get so quickly damaged as these newest Stern's. I have 20 year old WMS titles with no protection and far less obvious wear - some with almost zero wear . It's either the clear or a vastly overpowered coil (or both). I'd eventually try swapping the coil for further piece of mind.