Some of the old stuff is still really good. I sometimes get some old stuff from a dump store and I think people can drop their old army stuff there (like their dad's stuff that they found in the attic or stuff from while we still had conscription here. Some of that stuff is timeless.
I think I got some mess tins that had 1985 stamped into them or something. If they're in good condition still work awesomely. And t.b.h. some designs are so basic that is hard to see a difference. I mean, with the mess tins, the newer stuff looks a little more modern, but functions exactly the same.
As an aside, the past 15 years it seems like a lot of companies are designing products so that they purposely fail after a few years. That way you have to keep buying new ones. I feel like it's gotten harder to find the strudy rugged stuff thatll last a lifetime. I know it's still there, but it's harder to find, is all. The old stuff tends to be really sturdy and meant to last a lifetime.
Im not saying you should lug extra weight just because, but sometimes older is better. Sometimes the reverse is true too, though, so I recommend you pick and mix.