If you go to the web site benjammin listed in his first post or the AeroVest site, you will see all of the users are weaning the vest without a jacket. Now I realize this is primarily for sales reasons, but still in my humble opinion somewhat misleading.

I can think of a several scenarios (our team has rescued dozen of people without jackets) where one is without a useable outer jacket (not smart but still the reality). How many times have we discussed someone or groups of people just going out for a day’s hike, it’s warm, so they did not bring along a jacket. The weather changes or they get caught spending the night in the woods without proper clothing. Perhaps they did wear or bring a jacket (likely cotton or lightweight nylon) and got it wet, the insulating properties are lost or worse are resulting in additional heat loss due to convection. The question remains, is this vest effective as a stand-alone piece of equipment or not?

A heatsheet will provide greater body surface coverage, better convection heat loss protection, is much cheaper and packs down to the same small size. You can place a slit in the heatsheet and use it as poncho, use it as blanket, wind-block, a heat reflector, vapor barrier, lean-to or A-frame shelter just a much more versatile piece of equipment.

Pete