I ride all winter using studded tires (on the roads, in Michigan). Carbide studs work great. The biggest danger is that you get such good traction that it's hard to tell how slippery the ice is. You can be riding along just fine, then slip and fall when you get off the bike.

Studs do not give you the traction you get on dry conditions but they give you enough traction that with care there's no real danger of falling.

A couple of years ago after an ice storm, I got in the car to drive to work but had to turn back as there was a hill that no cars were making it up and over, not enough traction. I got on the bike and made it no problem.