Would that be the SXP you were inspecting?
http://www.winchesterguns.com/produc...21C&mid=512252
Spend some time actually handling a variety of shotguns, and shooting them if you can BEFORE you buy. Some ranges and gun clubs/trap and skeet ranges have rental guns if you don't know any shotgunners you can ask for help with this.
Better to work off your own experience than what a bunch of strangers on the net tell you IMHO.
Best bet for what you describe IMHO is one of the major manufacturer pumpguns with a wide variety of extra barrels available. I like Remington 870s but you may decide on the Winchester or a Mossberg. Whatever you like will work. The two barrel/one shotgun set is even offered as a combo in some cases, it's not as if it's a new idea. A shorter barrel, maybe with rifle sights, for defense, and a longer vent rib barrel for other stuff.
Get someone for whom this ain't their first rodeo to show you around shotguns a little. Don't be embarrassed - it'll save you time and money in the short and long run. If you're in my area drop me a PM...