Mac, I have both the Wiggy's unit and my vintage down bag with aftermarket vapor liner ( so I am not prejudiced in terms of system.) If you go to the WSI site ( listed in survival schools), Chris Janowski has a write up on wiggy bags ( he is a distributor) and his tests in Alaska. I like the wiggys primarily because they loft like down with easy maintenance. My down bag has 30 years of memories ( and stink) embraced in those feathers. It was professionally cleaned once. The wiggy can be tossed in the washer.