Don't fool around, take the SBEII for the versatility. You can get a fair price on synthetic stock models. Otherwise, pick up the new Vinci. I have been shooting an original HK imported(1992) SBE with a 26" bbl. Love it.
I have been shooting an HK import SBE since 1992 and over decoys I always use 3" for my 1st and 2nd shots with a 3.5" for my last. If pass shooting(I hate)I use 3.5" always. The ammo is much better now, so I rarely use 3.5", except on snow geese.