The ballistic performance loss of shorter barrels is minimal. The advantage, if you're calling from a blind/stand for an ambush is less likely to get hung up on brush and/or spook the bird as you manipulate the shotgun.
In CA, the turkeys got thick enough, we didn't have to deal with calling/stands. Instead we shot them on the wing while pheasant hunting.
If not already shooting TSS, I'd likely put my efforts there vs changing barrel/gun.