Safelite is great for 95% of the cars out there with standard glass (OEM or not).
But throw them something even a little bit out of the ordinary, and it's a cluster****.
I took my 2005 Merc SLK350 w/sport package to them for a windshield replacement. It took them THREE TRIES to get the right glass installed. The first two, which were OEM because there isn't enough demand for that car, fit correctly, but the inside trim was wrong -- the mirror trim didn't line up right. So they trashed the first one, put in the correct OEM replacement and it still didn't line up right. So they had to trash the second one (at their expense both times). By the third time, the finally got the proper glass for my car and trim, and installed it. Once they got the right glass, they do a great job of installation.
For a Tesla replacement, surely they'd be getting the OEM glass from Tesla. I'm sure there isn't any third-party glass for the Model S.
Also, I'd highly recommend dropping the car off at their shop to do the install in their garages, and not use the mobile install service. Most glass glues need time to cure, and if it's too hot or cold outside, that could affect the seals and install quality. When they did my glass (all three times), they let the car cure inside the garage for a day so it was unaffected by outside temperature.
I also had problems with Safelite when my insurance co demanded I go through them to replace the glass in my Delorean. After going back and forth between Safelite and my ins co several times, Safelite flat out refused to work on the Delorean, so I had to take it to a Delorean repair shop to get it done correctly ($1200 covered 100% by insurance). This happened twice.