Typically the dealer will not do the install, if you opted for BMW glass, they would have a glass company come do the install anyway. Also, talk to your insurance company as around here they will do OEM glass for the first year you own the vehicle, then only aftermarket and you have to pay the extra.

There is nothing wrong with PPG glass, it may even be what is in your car as they do a lot of OEM glass.

I did have an issue once with my 2003 3 series where the curve of the aftermarket glass was a little off and the rain sensor would not mount correctly or work, so the insurance company ended up putting OEM BMW glass in the car and it didn't cost any extra when they had no choice to make it work.