ive found there to be a fairly substantial difference.
Of course thats an opinion and we all know how those are..
But heres how i see it, and yes i'm likely full of crap!
Because of the payload advantages, i figured that i could drop to size 2 instead of 4 and have the best of both worlds, (lots of pellets and energy)
from my experience, the 2's fly farther and hit harder too, so thats my explination for taking the occasional longer shots..
crap or not, my kill percentages went up substantialy, as did the pain in my shoulder, and the drop of cashflow leftover in my wallet...
--- now im back to 3's for the regular ducks, but the geese get 3.5's and so do the turkeys..
i also like the 3.5's when jump hunting ducks, at longer ranges, when they are headed away