Hi...
I agree with Birddog here...
The 3.5 is just too much... except for buffalo or elephants... and I don't want to go there... The Benelli auto I have (Sport II) is sweet and fires hi-brass 3" pretty easy... but it is not a field gun so I would look at the 'Legacy' series... same gun...field rib... My prior shotgun is the Rem 870 3" mag... and I never failed to hit and kill what I aimed at with 2.75"... much less the occassion 3" I fired... the extra powder OR shot you get in 3.5 just isn't really needed... Not sure what they intended 3.5 loads for... other than 'BIG KID on the block' marketing...
I would recommend Auto only because the second shot (if needed) is quicker... and you are busy aiming rather than pumping... (more fun). BUT... the cost of an auto for field work... well...