Thanks for the Blizzak tip! I'll put those on the list of list of tires to consider.
Subaru dealers tend to be staffed with people that can't get up to Moron status.
As for running 15" steels, it's an excellent idea. We're running 15" steels on our Forester and it works very well. No worry about expensive alloys in the winter and the taller/narrower snow tires actually work better. A nice bonus was that the wheel/tire combo intial price was about the same as the 16" snows alone, and then we'll save some money every time we get new snowies.
BTW, we're running Blizzaks on our Forester, and they turn the little tall-sorta-wagonny-thing into a snow-eating beast in the winter. I spend plety of time in the mountains on some pretty poorly maintained roads (and some non-roads, too) and there hasn't been a single moment when I thought we might be immobile. On a few occasions, the snow was deep enough that we had to push open the doors through snow once we were stopped. Now, the Impreza isn't quite as tall, but it won't make a lick of difference.