I agree that the Bridgestone dual compound is worthless. I had some Dueler AT's and the last 30% or so of the tread was noticeably worse in slick stuff.

As far as wide vs skinny, if you want flotation, probably for off road situations, then wider will work better. But, for on road, it comes down to personal preference. A skinnier tire will have more force per unit area, but a wider tire will have more units of area in contact. When determining frictional force, contact area has no effect whatsoever. The only things that matter are the weight of the vehicle and the coefficient of friction between the tires and the ice/road/whatever.

I have found that on snow covered roads, a day or two after it has snowed (when traction is the worst) a skinnier tire seems to track better. I won't say that it has more grip or bite on the road, since I don't think that's true, but I do think that being narrower allows the tire to be affected less by the grooves and variations that form in the packed snow/ice. Plus, once the streets clear, you've got less rotating mass for all your regular driving, which helps in the gas mileage and acceleration departments.