Are stainless barrels better then regular steel barrels?

A few years back I built a Mk12ish upper with a steel Daniel Defense 18" S2W barrel w/rifle length gas system. I haven't found any Mk262 ammo for it. However, it really shoots Hornady Superformance 5.56 75 gr. pretty good. I'm happy with it, it's a nice range toy.

NYH1.