So the 5 oz XP I refer to is a synthetic insulation that a company called climashield makes. I put the fabric under the foot and up the heel both for comfort and for something that runs the length of my foot so when I want to walk around camp, I have something protecting my socked feet from water, dirt, etc. I've found them to be highly versatile (in my limited field usage of them) as both an insulated mitt and an insulated bootie.
Dyneema is actually a very high tensile strength material (very similar to or the same as kevlar, the stuff they make "lightweight" bullet proof vests out of. When I say dyneema, I'm referring to the black fabric with the white gridstop pattern (which is the only dyneema actually used in the dyneema gridstop fabric). The black is a high threadcount, urethane coated nylon, I believe.