"So well a 3 AAA battery headlamp may not be regulated, it will for the most part produce constant light until the voltage drops below 3V and then you will quickly notice light drop off."
That's not been my experience with the non-regulated 3 aaa headlamps (mostly petzl) I've used in the past.
I notice the change in brightness very quickly, and while they do last "forever", find that the vast majority of that "forever" is at well below the stated lumen output level.
Maybe if I always ran on low it wouldn't be an issue, but once the drain starts being noticeable, the low modes are now too low to be useful.
Another thing that bothers me about it is working in 3s, 3 alkaline triple a's (~34g) is fine but I've got to have 3 more to replace, and I find it easy to get the fresh and drained ones mixed up, 3 double A's weigh about the same as 6 triple a's, but that's two backups, which I often wont need more than one if at all looking at the numbers on something like a Zebralight.
Looking at the numbers on some comparable regulated high output lights that use either 3 triple a's, or a single double a, at the same ouput levels, the math is showing me that the double A's come out very close, depending on the LEDs.
Yeah, I'll be changing batteries more often, but in this scenario it seems more versatile to me.
Right now I'm leaning towards some Zebralight floody, with a backup high power torch, I like the Spark SD52-NW, *but* 4.2oz for the package with an eneloop, having to use two batteries in it, the ZL H502d High CRI Daylight tint AA Flood, with two eneloops would be 3.8oz.
It's a hard decision though, as the Spark with the extra lens would allow me to leave the flashlight at home for lighter trips, and supposedly has a more comfortable head-band, but is an ounce heavier on the head, and would require lens changing for hiking with it, and more fiddle factor likely.
I am probably going to go with an 18650 powered torch, but don't anticipate taking backup batteries considering the run times. I want the extra output and the long single cell run times, but will likely never drain one on a short to medium length trip.
Does anybody else know of a lamp like the Spark SD52-NW that can easily convert from a full flood to spill or spot beam, in a single AA format or a lighter overall package?

