I would not ever buy a 3 1/2. Too much recoil for little added benefit. Go to Ithaca Arms website, and under facts look at the article about 3 1/2 inch shells. They put out more foot pounds of torque than most elephant loads...

Just something to think about...

BUT...for those uses listed, I would personally go for the lightest gun. Swinging it onto a turk is no big deal, but if you're also going to have to swing on geese and lug it around the field for bunnies, that extra weight will add up to a tired shoulder eventually---maybe not now at your current age, but look into the future a little ways...