bjorn, I would guess that after you use it in a real snow, you'll find that the wide blade will push the tractor to the side when a load of snow gets built up. Using rear chains will be a big help (sorry if I am repeating someone's earlier advice) in controlling that- and providing traction in snow.
You can always cut it down later. I suppose you could always weld the cutoffs back on, as far as that goes. I found that my biggest problem with a rear blade was leveling it for sloped or crowned surfaces- now, our front plow floats from side to side, and is heavy enough to follow the surface, so no problem.