The 930 is a great semi auto for the price! Should you go with just a 500 pump? Well the question is whats it for? Home defnce pump! Racking of the slide scares the pants off of most anyone! They are also very reliable more so then a auto! Most bird hunting situations beginers are far better off with a pumpas every novice hunter with a semi auto tends to shoot behind the bird on follow up shots...now sporting clays, or a more advanced bird hunter a semi auto is a good way to go... but both will work in all aplications however if home defence is primary I would go pump if clays is primary semi auto Is a better idea. As far as the mk2 I have no real experince I did hunt on a wma area with a fella who had one I asked him about it he said it was ok and I usally seem him with a 870 might say alot but that's all I know about it.. at the same time if it were as good as the 930 I would see alot more!
Edit: Also if you go 500 pump dicks sporting good sells one with a slug barrel and a feild barrel for 300 bucks has a scop mount on the slug barrel good if your gonna hunt not so much for home defence