That thing looks like it handles like a D8 cat.
Sorry, but I prefer a nice English stocked double for bird hunting. Haven't seen too many Saigas in trap and skeet, either, not on the Olympic level or in serious shoots. I have a pump and an auto. No, neither holds 20 rounds, so what?
It is what it is, I guess. Far as the topping up thing, you'd change tactics with a box mag gun and do your tactical reloads just as you do with a handgun in IDPA, yank the partial mag and stuff a full one in while stickin' the partial mag in your waist band or somewhere. You wouldn't carry loose ammo, just full magazines. Of course, in real life, you will have your shotgun and perhaps a butt sleeve with five rounds. You ain't going to get up and put on your tacticool ammo vest to investigate a bump in the night. If you are, I seriously question your state of paranoia.
Me, I have a 20 gauge coach gun in the bedroom, two shots and five on the butt. That's more'n enough. I ain't taking on a company of Al Qaida. It's for if some determined intruder decides he wants in my bedroom past the locked door. He won't get far with a load of #3 buck in his face.
If you honestly believe you're going to have to go to war and bring your own weapon (who knows, but I ain't plannin' on it at age 55) I reckon you might "need" something like this, though I'd rather go to war with a rifle.