I'll share my experience.... I've put maybe 70 days on my cloth one's so far. They haven't begun to break down, and are oh so comfortable. As to what they do for me... they are a custom liner that greatly enhances both fit, and function of almost any ski boot. They are more supportive, and don't break down as quickly as most stock liners. It's the only custom liner I've skied so I can't compare them with others. The nice thing is they can be refit to a new shell if you want, and spotfit by adding material to the liner as opposed to using external shims.