I think the variety of opinions here shows that they are all about equal. I loved my Mossberg 500, it was such a sweet gun. I also like the 1300 Defender a lot. I could take or leave the Remington (if you're giving, I'll take ) but purchasing go with what fits you best and you are most comfortable holding, carrying and shooting. My personal recommendation is the 500 or the 1300 both in 12 ga for the all around performance.
Someone mentioned earlier that one them started the slide back when a shot was fired. That is a natural function of recoil. Every pump can do that, just hold the fore stock with a little backward pressure and see what happens (you may be doing it unconsciously). That little pressure is multiplied when the recoil comes into play and the bolt locks are released. The best way to check the speed is the length the pump has to travel (i.e. a 3 in pump is generally faster than a 3.5 in) and the smoothness of the action (that one you feel in the racking motion).
Someone mentioned earlier that one them started the slide back when a shot was fired. That is a natural function of recoil. Every pump can do that, just hold the fore stock with a little backward pressure and see what happens (you may be doing it unconsciously). That little pressure is multiplied when the recoil comes into play and the bolt locks are released. The best way to check the speed is the length the pump has to travel (i.e. a 3 in pump is generally faster than a 3.5 in) and the smoothness of the action (that one you feel in the racking motion).