You mean XCS? Besides the anti-corrosion coatings (internal and external) I don't think its any different than a regular 870.
With that said, I'd take the 590A1 over that gun. However, if you're hunting or exposing the gun to water/mud/whatever the XCS should technically fare better.
Is it just a toy/zombie-defense gun? If so, the 590A1 is bad-ass and hard to beat. The only Remington I'd pick over it is an 870 Police but you're talkin twice the price... that's a hard one to swallow. You have to go handle these guns if you get a chance.. the 590A1 is a hefty thing.