I installed two this weekend:
Black Knight
This pin has good playfield artwork with little wear, but lots of cupped inserts. It drove me crazy when the ball would roll over one and radically change into unnatural directions! The protector fixed that 100% and even gives off that clear-coated playfield look. Ball speed is still very fast and seemingly unaffected by the protector (I keep BK at around a 7 degree pitch). One problem I ran into was with the rollover switch for the Extra Ball/score at the end of the upper ramp...the protector "surrounded" that rollover and occasionally the wire for the rollover would get caught underneath the protector. The other problem was the right two ramps were now slightly lower than the lower playfield protector and the ball would "hop" a bit coming down the ramp. If the ball went slow enough, I could see it also getting caught in that gap and you'd need to nudge it out. I solved both problems by snipping the end of the protector by that Extra Ball/score rollover, then cutting that snipped part in half, then using them as shims for bringing the two ramps up to the same height as the lower protector. Overall very pleased.
Eight Ball Deluxe
This pin also has good playfield artwork. It doesn't have any cupped inserts, but the playfield is slightly rough in both the right and left inlanes where the wire lane guide meets the flipper. If you trap the ball with either flipper to set up a shot, then release the flipper, the ball stays were its at and does not roll down. You have to nudge the machine to get it started. I could try sanding those areas a bit more aggressively than I've tried, but that'll bring up the paint and then I'm faced with artwork touch up issues that are beyond my skill set/comfort level. Added the playfield protector, and the ball rolls smooth as silk now in those spots (and all over the playfield as well). I had to raise the inline 2x/3x/4x/5x targets a smidge to get them level with the protector so that the ball doesn't get stuck or hop, but that was no big deal. As with BK, action remains fast without needing to adjust the pitch (I keep EBD at around a 6.5 degree pitch).
I'm currently trying to get a non-working Mata Hari project up and running. If successful, I'll be adding a protector to that machine too!
Here are some pictures - Black Knight after the install, the protector piece I cut off of BK then cut in half to use as ramp shims, and the Eight Ball Deluxe after the install.
BK After 01 (resized).JPGBK Mod (resized).JPGEBD After 03 (resized).JPG