General comments: Excellent sleeping bag, much warmer in sub zero conditions than synthetic bags. Used in Scottish and Alpine climbing.
Pros: Very lightweight, and compressable, fits into a 35L day pack with room for everything else to fit in too! Pertex shell allows for warmth even if the bag gets wet, although I have not personally experienced complete saturation, minor damp patches have not been a problem...i.e. Platypus leaks etc.
Cons: Feathers begin to escape as soon it is used to any vigor.