Fit and feel. I have heard so much about "long" guns not being usable in grouse country that i could puke. If 26" is too long, then 26" will be just fine. Except talk to a guy with 26" bbls and he's considering having another inch lopped off his. Are grouse so scarce that the rare shot lost because of long barrels ruins a hunt? Shotgun fit and feel. Lack of fit or an unresponsive gun will spoil more shots in one hunt than an extra inch of barrel will over an entire season. I have two 16s from different manufacturers. Barrels are 28" and I reworked the stocks so that they mount and feel identical. One is choked IC and Mod, the other Mod x Full. If there were a local gunsmith I could trust, I'd have them set for choke tubes. As it is, the ICxMod gets most of the use.
RB