I have an old MSR Firefly...sort of a hybrid XGK/Whisperlite. They've recently reintroduced that style of stove with the Dragonfly. Works well in most conditions, but ALWAYS starts pulsing once it's fully warmed up. The one time it didn't work was the night rum froze...and in fairness, it worked fine once we got a fire burning and warmed up the fuel tube enough to get some flex into it. Tent poles wouldn't work either, as the shock cord had no elasticity at that temperature. That's the only time I've been truly afraid of the cold.