Lexan isn't going to hold up or play the same. It also will grow and shrink, which will cause ripples in the PF once you affix playfield components through it. You could free float it like a playfield protector, but many people in this hobby do not like they way they play.

One indictment on Mirco for me is the fact that I've shopped out a couple early 2000 era Stern machines with over 60k plays on them, and there was no chipping whatsoever, and the playfields cleaned up like new. I'm not counting scoop holes, because that's another animal. The shooter lanes were dirty, but that was it. TSPP, RT and RBION all had very durable playfields in them. The clear does not seem to be nearly as thick on them as well. So what changed? My GOTG has 13k on it, and still looks great as well.

Shipping a piece of wood from one part of the world to the other can have an effect on it. If the relative humidity in one place is different than the other, I could see it causing a warp. I have seen some peculiar things happen to materials I have shipped by truck from the east coast to the west coast of the US. We think going over the rocky mountain range during certain times of the year can sometimes have an effect on our goods.