I had an object strike my 2015 Yukon XL when it was about 4 months old. It shattered/crushed a large area just below the roof line of my windshield. I have the forward facing lane tracker/collision avoidance sensor(s) behind the rear view mirror, and "collision avoidance Head up display).
I called my insurance company, (AAA of So Cal) and they called/referred me to SafeLite (I had SafeLite repair a chip in the windshield on my 93 C3500 a few years back and they did a great job, so I was on board).
It took a week to get a GM Windshield (the adjuster even pointed out, because the vehicle was so new, he wanted to make sure it was factory parts, not aftermarket) and SafeLite showed up, removed the old windshield, and installed the new one without any additional issues. He disconnected the battery, and put the new one in, then reattached all of the hardware (the new windshield came with the brackets/mounts attached from the factory). He was done in about 2 hours, did it all by himself with his "special" tools and mounts. I was charged my deductible, less a "discount" for using Auto Club's tech (SafeLite), so it was $200.00. (250.00 deductible, less 50.00 discount for "in house").
I asked the SafeLite guy what it would have cost had I not had insurance and had to pay cash, he said the windshield alone was around 1000.00 and installation would have run between 200-300. So, your posts of 840.00 installed from the dealer seems a bit on, and depending on how you look at it, cheaper? I will say, that the next year when my insurance bill came due, it went up 170.00, it since went back down, but they get their money back one way or another.