I put these boots to the test on Denali. They sailed me up and down the mountain attached to snowshoes, skis and crampons. I wore them nonstop for 21 days (when I wasn’t sleeping or lucky enough to be in my down booties) and never got a single blister. Nothing broke off despite the abuse I gave them: kicking blocks of ice while building walls, playing glacier Frisbee and lacing as tight as possible at times.
My feet never got unusually cold, but I used over-boots above 17,000 feet. A problem with this blend between a hardshell and a softshell is that you cannot leave the shell outside overnight. We had three guides in a tent without much extra space. If left outside, the outer shell would freeze or fill up with snow which was not good because the inner booties are too thin to keep your foot insulated from the outer boot. After a while I developed a system of keeping them between the two pads under my feet, but this might be uncomfortable for some people. The other issue with this system is that the inner bootie is molded and not designed at all for wearing without the outer shell. I like having the ability to wear just the inner shell if just getting out of the tent to pee or some other short trip. Overall, however, the Ice 9000’s comfort, warmth and lightweight design would compel me to use these boots again on Denali or elsewhere.