Go with a selectable locker in front, if you really need one. I'd double check what axle you are running, and run the numbers to make sure you have either a power or traction limit to keep from blowing expensive parts. Jim Allans 4 Wheelers bible has a good section on this and makes the math easy to understand.
Any kind of traction adding dif. is going to have peccadilloes, it just a matter of figuring out what you are willing to deal with. The problem on ice/snow is once the tires start to spin, they are both spinning and your lateral traction has just gone out the window. Add that to the pronounced road crown generally found in snowy climates, and you end up with the automotive version of the Harlem Shake.
Personally, I've had so many outfits with rear lsd/locker/spool that an open dif causes me more problems then the locker ever does. In some ways a spool is the easiest of the three to drive on snow/ice, simply because you know exactly what it's going to do, torque is always going to both wheels. Once you figure out how much power you can apply without breaking the rear end loose, stay under that power level and things work pretty well. The problem with Automatic lockers and LDS's comes from power switching from one wheel to the other, depending on traction. Full lockers are a little easier to drive on the snow, because they recover faster from tires spinning. Once you lift from the throttle, and the carrier slows below road speed, one tire is free to spin faster then the carrier and the other tire, matching the roadspeed. Once one tire stops slipping, you have lateral traction again. With LSD's, you have to match both tires to roadspeed to regain traction, since it requires much more torque to slip an LSD clutch or gears than it does to activate the overrunning clutch on a full locker. This can require a delicate dance of adding and subtracting power until wheelspeed and roadspeed match again.
I know this flys in the face of common wisdom, but that's my experience.
Honestly, experience is the only way to make good decisions, and experience comes from bad decisions
Matt