I just found this thread _after_ I ordered my new winter tire set. Fortunately, everyone else concluded the same as me - the PA4s seem to be the way to go. I ordered 245/40/18s for the front and 245/45/18s for the rear, as that would have been closer (by percentage) to the current tire height; after talking with the folks at TireRack this morning, they suggested I also go with a square setup.
Tires to be delivered tomorrow - we generally don't have too much bad weather in St. Louis, but it does get cold and the PSS require too much white-knuckle driving in the winter. I'll look forward to everyone's updates - mine are forthcoming as well!