Sorry Paul but I disagree about studs being more effective at all let alone MUCH (your emphasis, not mine) on glaze ice. In the world of physics the studded tire is a more consistent performer in the glaze ice battle in that it will give the same response whether treated gently or harshly---it has been my experience that the mentioned "slowing rapidly on glaze ice performance" is because of an acceleration dump or other abrupt input change and studs are more predictable. However given smooth handling and advance planning, siped tires will still beat them in performance. I have traversed hills and stopped at intersections that had defeated all around me many, many, times over the 45 years I have been using siping exclusively---needed my chains on the ground only 3 times over that period. I run an all season siped tire year around. And siping also aids in tire life--with the exception of gravel roads,--tire noise, and ride.