There's no shotgun made(that I know of) that will shoot faster than an old style pumpgun that will let you hold the trigger down and pump away cowboy style. I've beat buddies(speed wise) that have very expensive baretta auto shotguns using just my plain old monkey wards model 35 or my old winchester model 12. I'm just a tad faster with the 35 though, because the grip style is a bit more comfortable for me.
One friend of mine, who has both the pump version of your gun, and your gun, and also a pump action 30-06 remington with hi-cap magazines(he's a huge remington fan), went clay pigeon shooting with me and the first time he heard me do my rapid fire thing, it scared the * out of him. He thought my gun exploded and he actually hit the dirt.
That pump action rifle is kinda cool, although I'm not too sure how usefull it is. With a scope on it, it's nearly impossible to stay on target while pumping it for a quick second shot. It sorta defeats the purpose in my opinion. I'd probably conclude that with a rifle that powerful and that powerfull of a scope, pump action doesn't give you any advantage over a bolt action.
In case you can't tell, I really like pump action. I'm also a little partial to 16 ga. Although, I must admit I find those really short 12 ga rounds made for cops very interesting. If I could get a pump gun with a really short action that only chambers those shorty twelves, I might like it better. Better yet, if someone would apply that same philosophy to a 10 ga round...a super shorty ten ga gun...now THAT would be quite the little scattergun. Something like that would most definitely cause me and my greenbacks to part.
I can't honestly say which is quicker, but some young cops kick my ass at every 3 gun match using 870 pumps.