I thought this article has some good points and seems to convey many of the things learned over the years.
http://chrisechterling.com/blog/2009...-sleep-system/
We are creating several zones of separated air space and looking to newer lighter materials to make up the construction. As each layer is employed it works together with the others to make up every increasing protection. We integrate both passive an active energies that enhance the physical construction if necessary. Weight precludes us from adding excess materials or extravagant detail so we work with voids ( air spaces ) and material performance.
As with many things this becomes as much about skill sets as equipment. Things like avalanches, crevasses, slopes, weather, hypoxia, hypothermia, etc...play critical rolls in surviving the environment. In talking with different mountaineers there is of course the old school vs the new school perspectives.
Basic information about the mountain.
http://www.peakbagger.com/peak.aspx?pid=271