All valid points, but a helmet and lights won't slow you down 10-15% like studded tires. That said, I have Marathon Winters which I used last winter. They're great on hard packed snow and ice, but terrible in soft rutted snow. I'm debating whether or not to get some more aggressive studs for another one of my bikes (a mountain bike) to use on really bad days. It may only be 2-3 times per year where the roads are unplowed, but it would make a big difference on those days. I could also use them for trail riding on the weekends, so they'd get a little more use.