Guys in my BMW forum have been able to get good glass via Safelite, but it took some conversation with them.
They will always default to their in house or whatever is most easily/readily available but it's luck of the draw. Sometimes you can talk them into certain things, but it's iffy.
I say they're shite because I've seen far too many stories of people getting the
wrong windshields installed, and that just shouldn't happen. Sometimes the glass is shitty too. I have had decent service from them for chip repair except when the guy thought it would be okay to lay his grimy "protective" mat between his tool box and the hood of my dirty car, let alone put anything on the hood in the first place. it left marks that required polishing to remove, of course.
Whats funny is the rest of the glass on the car is already Saint Gobain, at least on both of our MK7s. When my wife's car got broken into and they had to replace the rear window, Safelite had Saint Gobain to replace it with.