I have heard from many that 3" shells tend to outpattern 3.5" shells. Just got to to do your own testing though.
I recently obtained a Browning Maxus (installed factory full choke). Put a few rounds of Winchester Supreme 3.5" XX Magnum Turkey loads (2.25 ou #5, 1150 fps) through it at 25 yards. I suspect 60% of it didn't even hit paper (~2'x2' turkey target) though it did put 12-19 in vital zones...oh and did I mention my shoulder hurts?! Trying to figure out what turkey choke to purchase. I don't plan on doing any surgery out to 50 yards so I may go with a little less restriction than is typical. Thinking about trying a ported 0.670 or 0.680.
But ultimately yeah you are going to need a choke (factory chokes tend to be poor and factory full will be less than optimal) and you are going to want to pattern test your hunting load at multiple distances. I will probably pattern test twice at each of the following distances: 20, 35, 50 yards.