What is the general opinion of these stocks? are they more durable?

I like mine.

Polymer telestocks are a bit lighter.

Poly stocks rattle a bit less.

Poly stocks aren't as cold in the cold weather.

Alluminum stocks are nice to smash someones teeth in with [:D]

I only have aluminum, I don't have any plastics.

The main problem I have with the aluminum is that it will rip the hair right out of your face. I don't know if plastic has the same problem, but it sucks.

It's also noisy.

Other than that, I like them. I'll be getting a plastic one soon.

I've used both the aluminum and plastic ones. I liked the lighter weight (saved 8 oz) of the plastic one, plus it's much more comfortable to use in cold weather. Having your face stuck up against a below freezing aluminum stock isn't fun.

I did try some bicycle innertube tied onto the aluminum stock, and it helped, but it was kinda funky looking, and it didn't stay in place too well.

I haven't tried it, but I doubt that smashing someone in the face with an aluminum stock is such a great idea. You are likely to have a busted up stock, or break the pin that keeps the stock from changing position. Whoops.

I've read somewhere (maybe here) that when the two are shot or subjected to the same force, the aluminum will shatter while the plastic will crack or leave a nice hole.

Actually, nothing broke surprisingly. Looking back Its a good thing it wasn't plastic.