Just an observation, upon close examination of a MOP sharktooth-inlayed fretboard with very worn frets, the inlays were very scratched at a few places but it was not very noticeable. I imagine that the same scratches on acrylic mirror inlays would be more visible, but it wouldn't be so bad on acrylic inlays with something other than a mirror surface underneath. The presence of the strings also distracts from any imperfections, but my experience is very limited.