I've gone through three Duos as my secondary light sitting benignly on my head being used strictly as the backup to carbide (see that on my head in my avatar pic = Duo ~ 7 years ago, it is now useless: connectors in the base of the battery case (which cannot be taken completely out to be dried and cleaned = too corroded to send an adequate signal). Duo's are no less crap than Myos or any of the rest of them. It is the basic reality of electricity and cheapo conductor materials, combined with engineering that is more about appearances than the fixability of the lamp by a caver that make electric lights problematic for caving. Your LED may have soldiered on on THAT trip; but how many more trips of exposure to water until the connectors corrode? I can leave my carbide cap lamp sitting in a vat of cave for a year to collect moisture, come back, fetch it, clean it with muriatic acid and a bit of elbow grease, replace the seals and filters, and the flint (maybe the tip) and voila! good as new.
ADDIT:
Though I haven't used a caplamp carbide, only a remote-generator one, I'd assume from the fact that I don't know of anyone who has a caplamp one except possibly as an ornament or memento, and even including the many people who must have used one at one time I don't think I've ever seen anyone using one probably says something.
Like what? Cavers are no less ignorant and commercialistic than the rest of the general populace?
Re: your comment about things blowing up in crawlways: I cannot speak for the belt mounted generator things, though I will say those always have seemed problematic. But I will say this. If you hand a firearm to a cave man and say "have fun" you shouldn't be surprised if somebody gets hurt. Using a carbide properly requires a bit of training (at least for the cap lamps). If you do not get that training first, it is not surprising if you do not figure out how to use it, and maintain it properly on your own. Course you can always buy an electric which is as simple as flipping a switch . . . until you get in that mud-wallow section, where it might turn into an $80 piece of inert plastic!
ADDIT:
But most of the time, you're not using the heat.
I think perhaps your missing the point. The point is that a carbide cap lamp is multi-functional. When you need heat, you got heat! You don't need to carry some other device, you got heat from your lamp. When you need station marker, you got station marker. You don't need to carry another device, you got station marker from your lamp, and you got heat from your lamp, and you got light from your lamp. A rather pleasant kinda diffuse, warm, soft, glowing light at that.
If I can carry ONE piece of gear that doubles as a screwdriver, pliers, and wrench, vs. carrying one of each, I'll go for the multi-functional tool myself.
ADDIT*2
I'd reckon it means that they didn't sell you a caving light, just a general-use headtorch. For caving, I guess Petzl would recommend a Duo.
Whah? It doesn't get wet in the mountains? It doesn't get wet canyoneering? It doesn't get wet when big wall climbing? It doesn't get wet when camping or hiking? It doesn't get wet when kayaking, rafting, fishing, hunting, canoeing, or any of the other myriad activities that Petzl can pass off their gear as being well-suited for?
The crap they sell us is poorly designed, cheaply-made, uninspired junk. The only reason their ropes hold up is they know people will be dangling on them.
It is too bad that the company that makes Wheat lamps or other similarly tough (and extremely heavy) lighting devices does not apply their standards of durability, and excellence to cutting in to Petzls market on lights.
I admit it. I use a LOT of Petzl gear, and in general it works. But electric lights send me to the moon. I should NOT have to replace an electric light every 2 or 3 years simply because I do hard, wet, muddy caving! But I have! Consistently for 20 years had to do just that!
I will also admit: Petzl has begrudgingly reimbursed me a number of times for Duos, etc., that clearly underwent use-induced design-failure. I had to harangue them, but more than once they have given me a free light. IMO, they would be wise to stop monkeying around with these half-ass designs they use. LEDs, and high efficiency systems? Sure that is great. How about modularizing the entire set up so that if any specific part fails, it can be replaced? How about giving up on the whole "water proof" nonsense, and simply make it water resistant, but also easily, readily, and clearly disassembleable COMPLETELY. Let me get the thing FULL of water and gunk, bring it home, take it COMPLETELY apart, clean it, dry it out, put anti-corrosive on it and put it back together! That would be fine and dandy. I believe there are a couple of cheapo brand electric lights that one can take COMPLETELY apart allowing ALL the conducting parts to thoroughly dry and be individually cleaned; forget what brand it is, IIRC THe Fisher Ridge cavers use it as their primary tool. Why can't Petzl come up with something similar? Cause they design lights that look sexy on the outside to the climber, supa-scuba, REI, fashion-plate-environmentalist crowd, not for cavers and hardcore outdoorspeople.