How about "regulated with moon mode?"
I used to think unregulated would be better because that gave you the option of extremely low light that would bleed the batteries dry if you had to. I've bled zinc carbon cells down to 0.1 volts - yes, that's not a typo. Couldn't believe it on the DMM either, and the best part is that it still lit a Lux3 at 30mA, brighter than a fully charged ArcAAA!
These days I prefer it done KL1 style, because I hate having less than optimal light output and change batteries before their time is due. The KL1 gives me 2 hours in regulation, it flickers to warn you that the batteries are going (not sure if that was intentionally designed, but it sure is useful), and when it stops flickering you still have 5 hours of emergency power to get you home as it goes into direct drive and bleeds the cells dry. I've done 'dry runs' of around 4-6 hours just to see how far it will go and believe me it WILL suck the cells dry just as effectively as a dedicated lantern I built - down to 1+ volts, which for a CR123 is as dead as a doornail.
The lantern was built as a battery eater, direct-driving a Lux1 off 2xCR123 cells without even a resistor in series. Loading fresh 123s into it will destroy the Luxeon in VERY short order, but depleted CR123s run down to the point where they will no longer power a high-drain Surefire lamp still provide 10+ hours of diminishing light in it.
That having been said, backup lights are a must. Carry your Arc or CMG Inf Ultra.