After the power window on the driver's side of our car stopped working completely yesterday, I first removed the door module carrier, and lo and behold, there were some broken plastic pieces inside the door panel.
Today I bought a repair kit (part number 1JE 898 099 D) from the friendly VW dealer. To my surprise, even in this repair kit, the sliding parts where the clamping jaws for the window are attached are still made of plastic. I installed it like that for now because we need the car, and everything works fine again. However, I seem to remember reading somewhere that these parts are now supposedly completely made of metal.
I'm not sure if this will be helpful, but maybe it would be worth contacting Volkswagen and asking them. After all, there's no cost to asking.
As far as I know, the old guides were made of polycarbonate, which has good sliding properties but is prone to breaking.
It's possible that a different, more durable type of plastic is being used today, which would be worth investigating.
If the parts were made of polyamide, for example, there would certainly be no problems.