You are going to love the Beretta A400 Xtreme Plus!!!!! I just got one this year as well. Recoil with the 3.5" shells is nothing like my hugely heavy (with steel recoil reducer) Stoeger M3500 inertia driven cannon, and my lighter, Benelli Super Vinci, inertia driven cannon, both of which can't shoot 2 3/4" target loads.
It is a one shotgun gun, if there ever was one in my opinion. I shoot 3.5" #4's for ducks, through a Carlson's Cremator Ported extended long range choke tube. You should see the pattern difference just shooting the odd cripple on the water, over people shooting 3" #4's with the stock chokes they have in their guns. More pellets in the air means better patterns at all ranges!!!!
I don't go through enough shells in a season for the added price to be anything to consider. I only shoot a couple boxes a year for ducks.
Now go out and try shooting 3, 3.5" rounds in the 870, then try the same rounds in the A400 right after! You won't believe the difference!!!
My buddy was shooting my 3" Benelli Ultralight beside me with 3" #4''s, and he was complaining about recoil as it is inertia, and REALLY light. It's basically an upland gun where you don't shoot much, and with smaller, less powerful upland loads. I handed him the A400 and he used the same 3" ammo in it and he couldn't believe how soft shooting it was! He will probably buy one next year when the sales come out again.
Cheers,
Ian