Kind of a long read, but I wanted to put the info out there for reference.
A few months ago I got a crack in my windshield from a rock kicked up on the highway. It was too large to repair, so I started searching around the boards for advice and knowledge. I Read up on the wind noise issues and the proper install procedure to be used. Also read up on the comfort IR glass option,(51317059699), and calling the dealer to see who they farm their work out to. I got all the info I needed and called the dealer to see who they used to install their glass. They gave me the contact info of a small family type owned company and I called them up. We had a discussion that I wanted the comfort glass, did not matter if it was OEM or aftermarket,(it's the same I was told), no problem there. They then told me to call my insurance, (Liberty Mutual) and they would give them the approval. I did so, no problems. I called the glass company back to verify that they would install it per the BMW TIS in regards to wind noise. The phone rep was not comfortable with this, and transferred me to the manager. The manager and I spoke, and he indicated that he had never heard of any specs! THIS company installs all the glass for the dealership! I had printed the TIS and told him that I could give it to the installer, but he wanted no part of it. When he understood that I wanted it done correctly per the spec, he decided that he did not want my business! I was not being unreasonable by any means, but apparently he did not think that he could meet my expectations and did not want to deal with me. I had a few choice but mostly polite words for him, and ended the conversation.
I then called up Safelite, who I should have called in the first place.
From the get go they insisted they would do it correctly, and if I was not happy, they would make it right. So I had an aftermarket IR windshield put in with an aftermarket molding. On the ride home I noticed tons of wind noise, not sure if it was the bad fitting molding, the glass, or the install. The installer used the correct procedure and also had the measurement tool, so I chalked it up to the crappy molding. At this point I called Safelite back and said I wanted a new OEM molding put in. Since it had to be ordered, I noticed after a few days that the glass had some bending type distortion on all of the edges about an inch or two wide. The distortion was bad enough for me to have them get a new piece of aftermarket glass to see if it was just a one off defect, or if all the aftermarket glass had this. New glass came in and had the same distortion. I know for a fact that my OEM piece did not have this, so I called the insurance company to see about getting an OEM piece. No problem whatsoever, a new piece of OEM IR glass was ordered from Germany. About a month or so later, it arrived and was installed. Result: Zero wind noise, and no noticeable distortion, so I am a happy camper, I got an OEM IR windshield for the price of my deductable. I have to give props to Safelite for being courteous and professional throughout the entire process. They stood up to their promise and in the end did a great job. I would not hesitate using them again.
One point I want to make sure is clear, the aftermarket glass is NOT as good as the OEM stuff. All the windshield replacement companies swear up and down that it is the same exact glass but without the pretty BMW logo on the bottom. This was not true in my case. The distortion was so bad that I was willing to pay the difference if it absolutely came down to it.
I hope this helps others make a decision when the time comes to get new glass.