Wow - 400 hrs is nothing, if the machine was well cared for. We have a 4wd B5100D and its a little bull. As long as you don't hang any weight off the front and you're not trying to climb any hills or pull a trailer through a swamp, you'll probably not need the 4wd. Chains & counterweights/wheel weights will definitely assist any traction challenges you may have with the 2wd. This was our first diesel ag type tractor & intended to replace our Craftsman lawnmower, which kept blowing head gaskets and had 1 engine replacement. My intent was to sell the tractor when we got the
B2320, but it's such a great trailer hauler that my wife threw a fit when I proposed the idea.
A few thoughts after 7 or 8 years of use:
The front PTO, which you will need for a front mount snow blower, is almost impossible to find.
With only 12hp (10 at the PTO), you'll need to use that granny gear a lot if you ever do find a snow blower that fits & is in working condition.
The rear 3pt hitch has a lift capacity of only a hair over 300 lbs, which limits the range of 3pt implement that it can use.
As much as I love our little bull, I would recommend another machine if it's going to be your go-to machine for blowing snow and cutting grass.
Good luck & tell us what you decide!
Jim