window tint won't hurt your windows (and it saved my car from getting soaked and having glass everywhere when some jerk plowed into my door) The only problem I ran into was when the tint shop needed to pull off the tint to fix something, I think that hurt my rear defroster. 1. It is unlikely that they will have to do this if they are the most reputable. 2. they replaced my rear window, so all is well now.
Enjoy your tint!