I guess I am a disciple of Michael Mcintosh on the subject of gun barrel length. Barrel length for me is something that adds to the intangible "handling quality" of a shotgun. For upland game, as a general rule, 28" is my minimum, 29" my preference (esp. for 12 bore), and 30" my top end. I find a 26" gun to be a "quick starter/fast stopper" and 28"-30" more of a "slow starter/slow stopper" providing the follow through I desire to achieve forward allowance. These barrel lengths are generalizations that don't always hold, but they can be a decent starting assumption.
Getting down to brass tacks, the balance point is perhaps more important than the barrel length, although of course barrel length can affect the balance point. I prefer a balance point forward of the hinge pin by an inch or more in my upland game SxS.
