I'm interested in people's opinions on this as well. There are a lot of ways to look at it, but I personally like to assume that someday, possibly, I won't be able to get replacement parts, ammo, etc for the guns I own. I like to have more than I think I'll ever need, and while it would take a crazy expensive amount of ammo to wear out even one mag, they are still wear items. It's also nice to be able to have a good amount of mags loaded up and ready to go. I have two M82's, and right now I have 13 mags total. 6 per rifle was my original goal, but I think I might end up with 15 mags total to end on a nice round number. I buy the cheaper M82 mags, as the witness holes aren't worth the extra cost to me, personally, and I think that's the only major difference, although I could be wrong.