I have gotten so used to a 24" Barrel in my AL390, I hate the feel of anything else. I am hunting flooded timber standing in knee high to waist high water so the shorter barrel does well when I am wading to pick up decoys or put out decoys.
I sling it across my back with the chamber in the OPEN position so I know it won't fire. There is a code of sorts with Southern Duck hunters that no one else humps your gear but you. You always have a gun handy if you are in the decoys in case some fly in on you and they will on occasion.
If you go with a short barrel, either dove hunt a bunch or shoor copious amounts of clay birds to get that barrel length thing down on the pass shots.
"Without a rifle you are nothing, worthless, you are waiting for death, any minute, any second."
-- Aron Bielski