Actually, this isn't practical at all, and isn't really comparable to the AA-12.
The AA-12 is essentially a cross between an assault rifle and a shotgun. It's a manageable size for urban warfare (not much larger than a regular rifle), which is exactly what it's designed for. Pretty much, it's made for short to medium-range combat, especially CQC.
A gatling gun, on the other hand, is made solely to fill the air in front of it with flying molten death. While that's certainly enticing in CQC, there are several things that make a gatling weapon generally unsuitable for that particular type of warfare.
The first is size. There's a reason that submachine guns are still considered the kings of combat in closed quarters. They're small, they're light, and very maneuverable. While the AA-12 is without a doubt potent, and I'm certainly not an expert on the matter, I think even it's a bit large, all things considered.
This weapon is not only longer, but wider and heavier, and has a backpack thrown into the mix to make it even more inconvenient for the wearer in a tight spot. Since it's designed for a Fyunnen, I'd hope you're running a mission in a basilica instead of an office building. You'd be hardpressed to move through the area in anything approaching a timely fashion without a demolition team to accompany you and take out a fair number of walls and doors.
A second thing making a gatling gun bad for close quarters, and the reason almost all are mounted weapons, is weight. This figures in doubly so for this weapon. This type of thing is hard to swing around on your own, super strength or not. Taking into account that you're shooting nerimium bullets, I wish you good luck. 97 pounds is far too light for 2000 shells full of that stuff. There's a good reason Nepleslians put at most a thin coating on anything using Nerimium save their powered armor: It's really, really, really heavy.
Suffice to say, you wouldn't be able to use this thing in a city in any application save for fortification, and even then it will be limited to a small killbox that any marksman with a rifle could get rid of in record time. There's nothing else it can actually do. It's far too unwieldly for room-clearing, too short-ranged for fighting on an open battlefield, too weak to be of any use against powered armor, and too limited for use as a suppression weapon.