The standard barrel lengths are standard for a good reason. They work well for most people in most situations. Why do so many on this site promote all the weird stuff? You can go to extremes on either end, but to what purpose?
Odds are, a normal barrel length will serve you best. Pass shooting demands a smooth swing and follow through with a clear view of the relationship between barrel and target. That is aided by weight forward balance and a long barrel, and hindered by a short barrel. In the past some specialty waterfowl gun barrels were made as long as 36" for pass shooting. Now standard is somewhere between 28-30", a more practical and handy length. I do a lot of waterfowl hunting, and have for over 30 years. Personally wouldn't use a pump/semi with less than 26" of length for pass shooting. The only way to know for sure what's best for you is to try the model of gun you like and compare with another one you can borrow with a shorter/longer length.
FWIW, the top competitors at sporting clays never use barrels shorter than 26" and most use 28" - 30" because they shoot higher scores with them on the long crossing shots and the relatively long barrels are no handicap close in.
If you were wingshooting grouse in the alder thickets, your needs would be different, but for pass shooting waterfowl, the choice is pretty clear IMHO.