Like the other poster stated, it's federal law that hunting for waterfowl requires 2+1 capacity max. Also you cannot use lead shot when hunting for ducks or geese. If you use your home defense gun, not only will you need another choke/barrel, but you'll have to put a plug in it while hunting. It would be SOO much simpler to have 2 different shotguns-1 for hd, the other for hunting. That way you wouldn't have to worry about changing it around all the time.
As long as the choke is the same, the gun will pattern the same-regardless of length.
Sometimes you earthlings REALLY amaze me!