IMHO, I'd stick with the l/s rear and get some good tires on the truck. I do intend on running a locker on my F-150, but it's also being pressed into plow duty and I don't have a l/s rear in it.
I ran my Ranger around for years with an open rear diff, just ran good tires and weight in the bed. There were times that I had wished for a 4x4 or even a l/s rear in it, but it did alright, all things considered. Very rarely was stuck with it where I needed a tug.
And yes, a locker does handle WAY different than an open or l/s rear in the snow. I've had my choptop out in bad weather before and it makes quite a sight going down the road. I'm guessing it has something to do with being locked front and rear, but it'll "dogtrack" pretty bad going down the road in 4x4 with both front hubs locked in. And it will want to swap ends on an icy patch if you're feeding it gas and don't have the front locked in. Deff interesting to drive in the winter, but it does quite well in bad weather (I can't pull anyone out because it doesn't seem to weigh enough to get a bite, but I never really seem to get stuck either). Two winters ago I had it out in bad weather and was taking it up and down some dirt roads that were covered in hardpack snow an ice - which earned me some dirty looks from guys that had chevy 4x4 pickups and a couple jeep guys that couldn't make the grade. I just thundered along in 4lo with a big grin.