They are indeed pretty great. I've used mine for light downhill as well as skinning and it's fine.
For serious or longer duration running or skiing, the Zebralight is fantastic.
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If we're talking Nitecore, on paper I have yet to find a better headlamp for night skinning/skiing than their HC68 but I haven't pulled the trigger and field tested one yet.
95% certain though that their $30 cold resistant 18650 is actually just a $10 button-top Molicel M35A.