I got my smart in the third week of January and I had also had concerns about its winter driving abilities. I chose to purchase four winter tires after reading that the Canadians had better luck by doing that. I used to be of the frame of mind that put just TWO big lugged snow tires on my truck for better winter traction, but then I began to read that the current thinking is that it's the composition of the rubber that is almost as important as the tread patterns and it's as important to have tires that grip when you are steering as it is to have tires gripping that are providing the locomotion. At first I balked at the added expense but then I realized that my stock tires would last that much longer if another set of tires were being used during part of the year.
I've said all that to say, we pretty much drove our smartie with little or no restrictions and moved along quite well. Of course, during the heaviest of snows, we waited until the main roads had been plowed a bit, and we didn't try to plow through any major snow drifts, but we also didn't stay home because there was several inches of snow on the ground. Between the traction control, and grip of our winter tires, we felt quite safe and in control, much to the dismay of those owners of 4x4 SUV's in our neighborhood.