In reply to JJ Krammerhead III:
At those temperatures I'd consider thinking about vapour barrier liners to prevent moisture from your feet reducing the insulation of the main sock. You wear a thin liner, then the vapour barrier sock then your main sock. The inner sock gets damp but are easily dried out in the evening - obviously worth having a few pairs. The system feels odd at first as your feet feel like they are sliding around but you can climb OK.
boB
