These got their initial shakedown on the Bright Angel trail at the Grand Canyon during a major snowstorm.  Steep trail, sheer cliffs, snow and ice piling up and I had perfect traction the entire time.  I can't imagine not having had them for that hike.  My only complaint is that with the wet, sticky snow the spikes had a tendency to accumulate some snow at the ball of the foot which would then compress into ice and become uncomfortable to walk on.  That led to frequent stops to pry the ice ball off the spikes before proceeding again.  I attribute that mostly to the particular conditions at the time, but if that sounds like your typical winter environs you might want to consider other options.