I cannot agree with your logic, if you go dense shot, then a 3.5 has more of it! I do not disagree that the 3.5 may not be the cats meow but more of a better thing is usually better unless its a better arse kickin.
That's precisely the point: you don't need that much, because it's heavier for volume (i.e., sheds velocity slower, more terminal velocity). More is definitely not more in this case.
"More of the good thing" (shot), also brings more bad things such as recoil, over confidence (lots more shot makes up for poor wingshooting), a heavy gun that handles like a 2x4.
Ducks and geese can be killed efficiently inside of 40 yards with 2 3/4" field loads with 1 1/4 oz of shot. Beyond that, 95% of hunters have no business shooting at them, and most who have the skill are wise enough not to attempt such shots on wild birds.
