RE: 3 or 3 1/2???
I shoot 3.5" steel, hevi-shot and impact out of my nova for geese and ducks. I would go with a 3.5" for a few reasons, 1 there is no limit to what shells you can shoot. 2 Your hunting situation might change and it is nice to be able to adapt. 3 you have more options for shooting, you could use a 3.5" shell and open your choke up or if for some reason the birds are not quite close enough you could put in a tighter choke. The cost is not much different for a 3.5" over a 3". You can get a black Benelli nova for $300 and a camo one for $350.