> Double plastic boots are the standard of glacier mountaineering and most use them. Hoever, I've climbed Rainier (and most of our Washington volcanoes on many occasions) in leather boots.
I had a bit of an argument with the trip leader in Nepal, who wanted everyone to have double plastic boots. Sue and I refused and took light Scarpa leather boots of a generous size, with thick socks.
One member of the party who had plastics was in screaming agony up top: feet had swollen, but plastics don't move. No frostbite fortunately. Close. Hard to do good foot placement under those conditions of course.
Sue and I travelled much faster and had warm feet compared to the plastic-wearers.
OK, you might look silly trying to front point up an ice waterfall with our light leather boots, but they were great for ordinary walking and French technique (which is of course what the French technique was developed on).