The US military has been using the Spark Lite since the late 1970's and it has tested many times, including in Survival Schools in Alaska!.
I've seen persons with hypothermia who could not use any thing to start a fire.
Stu, I was first introduced to Spark lite at the Land Survival School, Washington, back in the late 80s. It was not as part of a survival kit but as the fire starting kit. I voiced my concerns back then about its use in the cold-land environment. The instructors agreed with me and said they prefer the magnesium blocks or metal matches.
Many skills are demonstrated in the ideal surroundings of a survival course by fit, healthy, well equipped and well rehearsed instructors and students. Most of these skills become very hard when used for real. Too much kit is give a place in the military because it works in the training environment yet fails at the first sight of real life contacts. Secondly, military survival is normally in the form of tactical escape and evasion. Fire is none tactical, so it is far less important in a military survival kit.
I have also seen people unable to do much with hypothermia. But, it is possible to do many things whilst you have mild hypothermia, to allow you to slowdown or stop the effects. Providing the tools you use do not require fine motor skills and that you can hold them.
Although the Spark lite does not require very fine motor skills it does require a tight grip that relies on that you have feeling left in your hand. The wheel is quite stiff and need quite a bit of pressure and feeling to turn. With cold hands this is painful, with no feeling in your hands this is nearly impossible to do.
I found that the spark lite is a lot easier to strike against my thigh when cold providing you can grip it. Interestingly if you can use a spark lite you can use a Bic lighter. Which has a far larger body, which allows you to grip it better with cold hands.
Can anyone tell me which military survival kits since the 1970s the spark lite has been included in, including date of issue and NSN No of the kit.