I now use a Duo with a 5-LED cluster, and I'm very happy with it for most situations. You do need to change the batteries as soon as you detect the voltage dropping off, and I do have a side-mounted Rage for pitches and avens etc.
I used to use an Oldham, but was never entirely happy with the light output, and I didn't like the battery weight/size/position at all!
I do like the light and warmth given off by acetylene lamps, but airlines don't like carbide, and caving abroad is what got me into Duos in the first place. Besides, more and more British caves are banning carbide, and I certainly don't want to be associated with the clowns who still seem to think it's acceptable to empty their carbide ash underground.