The boots we wore during Artic training in Alaska were of a type that could be partially inflated to provide dead-airspace insulation. The "Mickey Mouse" boots were warm down, but you had to change your socks two or three times a day if you wanted dry feet - they held in all your sweat. I can see the same problem with the inflatable vest - warm but a massive moisture barrier with little to no venting. Wouldn't want to be wearing it and doing anything resembling manual labor.