As far as the 4x4 vs 2x4 dually argument goes here is my take: NEVER give up 4x4 if you don't have too!!!!
I work for the phone company and we have LOTS of big 'dually's' -- we call them 'bucket trucks' and the have a LOT of weight in the back. With or without chains they NEVER out perform the 4x4 bucket trucks in the snow, never. In fact, my 4x4 bucket trucks are used often to pull out chained up 2wd bucket trucks.
Yes, people can learn to drive in the snow and ice in anything, I grew up in Canada and can attest to that, however 4 wheel drive is better in the snow, ice, mud, sand you name it. Doesn't mean you can't learn to go all sorts of places in 2wd and I have made it to my cabin in 2wd when my 4x4 failed to work. I chained up the backs (instead of the fronts) and made it up. Not nearly as well, but we still made those 19% plus grades.