a rather long time ago is used to be a caver (spelunker, potholer). The university i was attending had mining and speleology majors (and clubs). these lamps were commonly used as a light source in the local caves - limestone mostly - so methane pockets weren't a grave concern. they use a chemical reaction with water to make a Constable gas. In a cave - wet almost all the time and full of mud - battery operated flashlights were too fragile and prone to failure. if you had to pass a water or mud pocket, you just moved through it and relit the lamp on the other side. the light is bright and the lamp will strike when wet. You do need to refill it from time to time. the calcium carbide is granular and not liquid like kerosene. it will store a very long time if not exposed to moisture. There are only a couple of moving parts.
the carbide lamps work and are reliable but would no longer be my first choice.
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the calcium carbide must be kept away from water until ready to use. even a cracked casing can let humidity in and then the expanding gas can widen the crack. the gas is combustible and explosive like hydrogen or methane. the flame is very hot (could be good or bad) and mostly smokeless.
the modern LED flashlights (torches) are reliable (waterproof/crushproof) and use lithium batteries that last a long time. -to be fair, lithium batteries have to be kept dry too and the LED electronics is susceptible to EMP. if you can recharge the batteries, it tips the scales in favor of the LED version for me.
i've used both and that's my 2 cents worth.
