Gman, you may have already found this, but if you hit you tube and search "winter tires" or "winter tires vs. all season tires", you will find tons of info regarding winter tires and their compound. You can take that info and apply it to your situation. If you are willing to keep your eyes on the private for sale section, you may come up with a set of rims for winter tires within driving distance. (A tank of fuel is cheaper than shipping and much less hassle for the seller.) Maybe more up front, but the ability to simply swap tires and wheels makes winter tires much more attractive and eventually you will save the expense of swapping tires on your rims. It all works out in the end.
As for the actual need, I have not purchased winter tires for many years until now. My previous Subaru, as well as this one, does a fine job in the snow, but it will not stop any better than anything else. It is pretty obvious after doing research, that all season tires don't come close to winter tire performance when it gets cold out. When the temps drop, winter tires begin to out perform their all season or summer counterparts, regardless of dry, wet, snow or ice. All tires are a compromise based on intended use. I can't speak to the Blizzak WS70, but the WS60's get very high marks from the tests and actual users [for their intended use]. Based on the rave reviews on this board, those are what I went with. Ask yourself, are you really going to push your car to its limits when the weather is bad? Do you really NEED that final degree of super handling, which btw is diminished in cold temps anyway? If you want to maximize your ability to make an evasive move, stop in a shorter distance, and accelerate faster, (also possibly avoiding a fender bender from behind), then consider the best tire for the application and don't get too hung up on some high performance all season FWIW.
edit: I recently had this conversation with a friend who bought a new Outback recently. He said he wasn't going to bother with winter tires because he was on an even playing field right now with other cars on the road. His logic was that it is safer to be on an even playing field. My reply was this: "So having 10 cars on the highway that can't stop of perform evasive moves is better than 9? Of course if you think about it, that is ridiculous. It could be the difference of getting out of a jam or not.