Unless you shoot a lot of geese I'd drop the 3 1/2" requirement, especially in an auto. All of the 3 1/2" semi's are more sensitive to shooting lighter loads. I cannot see spending a lot more for a gun that reilably shoots shells I'll rarely if ever use and handicap myself with the shells I'll shoot 98% of the time.
There are more options in 3" guns and as a rule most of them still shoot light loads very reliably. They are cheaper too. For the very rare times you might actually need 3 1/2" shells there are other, more expensive non-toxc shot availible in 2 3/4" or 3" length that will easily outperform 3 1/2" steel. These loads are more expensive, and not what I'd recommend if you shoot steel at geese by the case, but for occasional use they are a better option.
If you MUST have a 3 1/2" gun I'd buy one of the Benelli pumps. I actually like the older, less expensive Nova better than the Super Nova.
With my money I'd buy a Benelli M-2. Although any of the offerings from Beretta are good too. Heard good things about Winchester, but no personal experience.