Yes, if I ride and there are several inches of unplowed snow on the route, especially with the Marathon Winters, on the power stroke my rear tire sometimes can suddenly slip sideways a foot. When that happens, I need a foot down NOW. I swap in platform pedals for those situations. Though I'm seriously thinking about getting over my attitude and just driving or working from home on days when the roads aren't plowed. It is kind of fun to have coworkers drifting in at noon, have them see your bike parked there and when they ask, tell them that you've been there since 6AM.

I have also switched to hunting boots in extreme cold - I don't think toe covers will make enough difference at -20*F - I'll probably wind up in boots again. But these toe covers seem OK at -5 or so, and I think they'd be good to -10 or a little colder. And most winters don't actually get colder than that, so I may not need to wear the boots this year. I really don't like them, they're like pedalling with bricks on your feet.

A warning if you keep your bike outside (in the garage or whatever) and want to swap pedals in the winter - a few years ago I swapped pedals when it was -15*F out. The aluminum in the crank shrank around the pedal's threads so much that when I finally got enough torque on the wrench to turn it out, it ripped the threads out too. Nowadays I do two things; first, I make sure the threads are covered with anti-seize compound every time I install pedals again, and second, if I have to take them out in the cold, I hit the aluminum with a torch for 15 seconds or so, to bring them up to something comfortable to touch (60 to 100 *F).