Harvey, I like the silk liners, used one this last trip. Keeps the bag from getting too filthy so I don't need to clean it, and keeps me separated from a dirty bag, if that is the case.
I think a liner really adds sleeping options. When too warm, I can unzip the bag, but keep the silk over me. It enhances the zipper adjustment options.
With my setup, a 20 degree GoLite bag and the silk liner, in the Sierra I slept sans-tent most nights, head sticking out, just wearing a fleece cap. Couldn't even wear a shirt most of the time. It would have to get much colder before I put my head inside the bag full-mummy style, or needed much clothing.
If you'll be inside a hut at 14K, you won't need a huge bag, since the hut will stop all wind circulation.
