I own a 500 and multiple 870s.

If I could have the feel and smoothness of an 870 with the action locklocation of a Mossy (behind the trigger guard)and the safety location of a Mossy (top of tang) or Winchester (crossbolt on front of trigger guard), I'd sell them all and replace them with THAT gun.

With that said, I've wagered the protection of my family on both models, and have had good experiences in the field with both.

I find that, to most folks, it comes down to 'feel', control positions, or loyalty to a given brand name. I don't think TOO much seperates them in quality or reliability.