Hey auto glass guys....

I have good experience with glass. Having worked for a large OE manufacturer and being trained in adhesives, I recommended the 3M product. As with anything automotive, there are many ways to do things. However, one key issue with rubber set glass like ours is being able to remove it at some later date, like glass replacement for instance. Todays urethanes have a very high tensile strength.It is designed to retain glue in style glass in the event of an accident. Lots of times you will see air bags blow the glass out when improperly installed...
Anyway, our rubberset glass was in no way weatherproof like todays cars, and I've found the aformentioned 3M product to fit the bill nicely. If urethane is used, you can guarantee ruining the gasket if you ever have to change the glass again. Also, any car that has a nicely painted glass channel will also be ruined on removal due to the cutting/scraping necessary to remove the glass. For E body cars its equally as no no as many urethane installations wind up with the glass to far in the channel with poor fitting moldings.
Just my .02!