PEI is crazy good right!?
I have been messing around, I left 2 shiny and smooth, one got scuffed with a scotch bright lightly, and one I sanded with 220grit. They all work great no differences yet. So it seems if you beat it up of scratch it no big deal just sand it down if necessary and keep going. the down side is I found a cold spot on one of my beds that things don;t like to stick to.
Have you tried PLA printing on it cold? I haven’t had time yet all of mine are still set to 60C.