I've always used a single home-made studded tire (sheet metal screws and an old mtn bike tire) on an old mtn bike frame for commuting in the winter. I recently moved and have added about 10 km to the commute each way, so am thinking about buying a pair of real studded tires. I'm wondering about people's opinions regarding Schwalbe marathon winters ( http://www.schwalbetires.com/node/1788 ) versus a more knobby studded tire. My thoughts are that the Schwalbe would give me a bit more speed, but I'm wondering if I'd lose a vast amount of general grip without any knobs whatsoever. My home-made tires have had a rather minimal number of studs, so that when I'm rolling completely straight I don't have any stud contact, and am relying completely on the rubber knobs.
I live in Edmonton, Alberta, so it's cold and icy more than anything (no mid-winter thaws until April/May), and my commute is completely road/bike paths, so I don't need any off-road capabilities (though I do ride in some fairly treacherous "ice ruts" on residential streets--so being able to get out of those is nice).
Any opinions regarding Schwalbes versus other knobbier studded tires would be appreciated. Thanks in advance.