when you have BMW body shop install the glass, they actually may subcontract it to the same company that you are dealing with - the difference is, in this case, a BMW stands behind its work, and not some other "no-name" shop, even if a technician from "no-0name" shop did the work...

and most insurances will cover OE glass, assuming, that you are going through the insurance... if, it is out of pocket... well... still, don't go cheap, when BMW sells you a glass, a lot of times the new glass has more connectors than the original had, as the new galss is an updated part, and the approved installers know what to do with them... on the other hand, if you get an older part for your newer car (they may have the same part number), you might be short on a connector or two...

not, that this will happen, but there is always a possibility... also, on a resale - when i am buying a car, i look at the OE logo on the glass - absence of logo would alert me to a possible collision, possible theft...