i had mine done 3 years ago and its not come through yet, in some light you can just see small areas of paint the size of pin heads starting to show but ive only noticed it as ive kept an eye on it. im currently having it done again but this time while the sunroof is out im treating inbetween the roof skin and sunroof tray and then fully painting it all inside then clear waxoiling too.

also i recommend whenever the roof gets wet open the sunroof to give it a good airing to try to dry as much of the moisture as possible.

dave