RE: Benelli Shotgun
I'd chose the shotgun based on what fits you best. I recently purchased a Benelli Steady Grip for that very reason. Of course the quality of Benelli was another selling point too.
As far as 3" vs. 3.5" boils down to personal preference. I've owned shotguns that chamber both of these rounds. The most recent 3.5" gun, along with my prior 3" gun were both turkey only models.
I've patterned a huge number of shotty's, with all types of chokes / ammo combinations and found a marginal, if any noticable difference when the best loads hit the target board.
The 3.5" shell was originally introduced for waterfowl hunting and has made a smooth transition into the turkey woods. For me, choosing the Benelli for that little extra umph was not worth the added $300 over the 3" chamber.
I've toyed around and found a load combo with my 3" Benelli that can hold its own with any of the 3.5" thumpers. The inertia mechanics of the Benelli along with the 24" barrel makes my Steady Grip a gun for all seasons.
Good luck with whatever you decide, IMO, Benelli sure won't disappoint in performance.