I just put a set into my 65 Mustang as the old post seals were crusted junk. Screws were a perfect match to the originals, fit was perfect, window movement is good, and I couldn't be happier. I have no idea what the expected life of these will be and won't know for a long time I imagine.
As with other parts that I am really pleased with I am buying another set as a hot spare. These might be tough to come by 10, 20, 30 years from now.