I live in Ohio, and during the winter months I do plenty of snow removal for my company. With several years of experience, I have used plow trucks with both 2wd and 4wd, and never have I once noticed anything in the 4x4s for helping me to stop in anyway.
Year after year it never fails when the "soccer moms in the SUVS" come blowing by me in a snow storm at 70MPH on the highway. I am in the weighted down plow truck, and there in there 4x4 SUV. Soon enough they realize just because they got a 4x4 SUV its not going to help them stop in any way or manner.
4X4s are GREAT, if your willing to spend the extra money, and feel your going to use it enough to justify it.