Has anyone tried one of these? I saw Les Stroud use one on the Sierras episode of Survivorman once upon a time, and my nearest army surplus store just started carrying them. Is it basically the same thing as an MRE heater with a reusable bag? It looks like you get 10 heating pads per set and my retailer sells them for $14.95. Worth it?

http://www.mreinfo.com/forums/viewtopic.php?f=12&t=4469
(I've got no affiliation with this link, it's just the most detailed info I could find.)

A few of my older Scouts use MRE heaters for both food prep and shelter heating. Wondering if this would be something for them to consider.