The only advantages I see to the 835 are the 3.5" capability and the ports, and neither is crucial.
A steady diet of 3.5" mags in a shotgun as light as the 835 will loosen your fillings, ports, overbore etc nonwithstanding.
Unless you're a way better than average waterfowl hunter with a recoil tolerance level much better than average, the 3.5 really doesn't offer much. Even then a good 10 gauge will be the better choice.
Mossies are good shotguns, tho not my favorite. Any of the family will give you good service. If I HAD to get a Mossie, it'd be an 835 for geese, a 590 for "Serious" shooting, or a 500 for GP shotgunning.