RE: How much extra range with 10ga
I can't speak for the patterning abilities of the guns but my buddy hunts with a browning 10 gauge pump, and I with the aft mention 870 super mag. Both can shoot the same loads, either the hi velocity load with 2 ounces or the standard speed 2.25 once offering from winchester, so I imagine they have roughly the same range, albeit the 10 may pattern better being it probably has a naturally better forcing cone (the gun makes my 12 gauge look like a 20 gauge.) The one nice thing about his 10 gauge it is weights 13 or so pounds so it really helps tame the recoil of 3.5 shells.