The "low end" aluminum lga771 Intel heatsinks were beasts. They were big. I never used the very fastest chips my old dual processor board could run....
Intel heatsinks are kind of crappy. The only ones I liked at all were the ones for the high end C2Q had solid copper slugs and even those are barely...
Plastic isn't going to last forever, that's a given. But it varies in durability, longevity. Here I am staring at any number of plastic vintage puter...