From a technical standpoint, they can be rather versatile.
For example the
Pedersoli Back Action Shotgun is perhaps in the top three of their best made guns. They are available in 12 or 20 gauge, and I have one in 20 gauge.
They are only choked in the left barrel, and that is a modified choke. Normally, upland game guns are Improved Cylinder (IC) in the right barrel, but Pedersoli left the barrels plain
which allows you the shooter to launch a round ball from them, if you want to go for deer or even hog. When using shot the right barrel is normally the first barrel used, and up close with a flushed bird the lack of any choke still does a good job.
The modified choked, left barrel gives you a good distance shot, having a tighter pattern at 35 yards or so, depending on the shot that you use and your powder load. So IF you need a second shot you have it. It also gives a much tighter pattern out to 30 40 yards, so gives you something for squirrels, and even for turkey.
For cleaning they are like a half-stocked, plains rifle in that you move the wedge/key in the forearm, and the barrels come away from the rest of the gun. The wedge/key is pinned so that it will not come completely out, so you won't lose it. A small bucket, some soap, some water, a nipple wrench, and some oil and voila, the gun is clean.
I've taken a lot of upland birds and squirrels with my 20 gauge, and I do recommend them.
LD