Fair enough, bird, eveybody's entitled to an opinion and opinions are what the OP asked for! As to the bulk-buying, goon is right. Mossbergs won the lowest bidder race I'm sure. However, you have to finish the race in order to have that lowest bid accepted. Mossbergs hold up just fine. Mine is an old one bar Mossy that is still going strong. I replaced the barrel with an accu-choke version (the original was fixed modified). It still busts clay and birds with a vengeance.
Now, don't get me wrong, I'm not slavish to the Mossy over the Remington. After all, when given the choice new, I picked the Remmy first, even though it was more expensive. The Mossberg I purchased used was in excellent shape, though. After using both, I have found I really prefer the layout and the feel of the Mossberg. There are several things I like much better with the Mossberg. For instance, the lifter remains in the up-position until you cycle the action. Therefore, when you load the magazine, you don't get pinched - and getting pinched on a cold, cold morning after firing at some ducks isn't nice. Worse is when you don't shove that last round all the way and it backs out above the lifter after you remove your pinched thumb and jams things up with a live round in the pipe. I also like the safety as it is identical to my Savage 333. Both shotguns shoot the same, so I'm not trying to transition between them. No slapping the trigger guard on the Savage. Back when I regularly used my Savage 720 based on the Browning Auto 5, the Remington was a natural because both shotguns have the safety in the same place. No transition there. If I were still rabbit hunting with that 720, then the Remmy would be ideal to continue to use. Should I decide to return to that old 720 for rabbit, then I might find myself using that 870 for ducks (yeah, I can use the 870 for rabbit, too, but the 720 is set up for lighter-kicking loads, has a shorter barrel, and is already choked ideally for rabbits).
In any case, sticking with an 870 and getting proficient with it is the best course of action. It would make an excellent home-defense shotgun. Of course, so would a Mossberg, which as bird has pointed out, can be had in excellent condition cheaply on the secondary market!
Ash