I did a mountain of upland/waterfowl hunting with my 12 S/S back before steel shot came around. Ptarmigan are a whole lot like chukkar or other grouse in how they fly and where you find them, making a double really handy. I smacked pheasants and dove too, basically not feeling undergunned at all compared to using a cartridge gun. Quail weren't too bad, mostly because it handled well and the caplock was quick. Did a bunch of duck hunting too, but got rid of the gun when steel came along. Really regret it now, because bismuth is available and could be substituted.
My old S/S didn't have chokes, and after working with some recently that do, I wouldn't buy one with chokes. Not PC, but when working without chokes you can go ahead and use plastic wads (Power Pistons or whatever) to produce "choke" in your patterns while making loading really easy, compared to getting around a choke in the barrel. Found an article back in the early 80's that recommended it and gave loads. He said that leaving the "wings" on the wad whole gave close to a full pattern. Cutting them to half length was about like modified, and cutting to 1/4 was about like improved cylinder. My trips to the pattern board verified this. Really handy, because you could adjust your "chokes" in the field to match the conditions, as well as have "choke" performance in your loads without the loading hassles.
I'm close to buying another S/S now, and torn between trying to do everything with a 12, or spending the extra bucks to get a 10 and a 20. The 10 would have benifits over the 12 with waterfowl, while the 20 would be a whole lot more fun than a 12 for ptarmigan. The 12 would be about ideal for pheasants, but I wouldn't be handicapped too much with the 20. Nuff to make your head spin.