I have a 2009 Outback, and have done a ton of reading about the "ghostwalking" thing. While some people have reported it fixed by realigning with weight in the back, and I think there was an updated TSB for aligning those model years, it generally seems that a given car either does it or doesn't do it. I've got about 195k miles on mine, plenty of them in the winter, with no sign of it yet. If I had a car that was displaying that behavior, I'd probably get rid of it, rather than start down the rabbit hole.
Outbacks should all be amazingly good in the snow, once you put good tires on them. If yours isn't, something is definitely wrong with it.