This winter has been especially snowy for Minnesota, and I've got along fine. I keep my Roadster in a garage, which is key: a good blizzard, dumping 4 feet of snow on the top might be more weight than it can hold.
I bough Blizzaks for all 4 wheels. My mechanic said the nature of those tires is that they are slightly damaged every time you pull them off/put them on, so I made these my "winter" wheel/tire set, and am buying a new set of wheels for the summer tires.
I've driven through streets covered with 4-5" of snow, and haven't been able to spin 'er out yet, even when I've deliberately tried. Full set was about $1200, but worth every penny, IMO.