yowzer
Enlightened
I would guess they made the change because more efficient LEDs are available. Why wouldn't they make the change? The light is 3 years old, so it's no surprise leds have improved in that time.
There haven't been any new developments in the XR-E front in a few years, and putting in an XP-E or other newer LED would require a major redesign of the optic or going to a different beam profile (And the beam that the LX2 sports now is one of the 2 big reasons why I love the light, the other being the UI). It's not something I'd expect to have seen any incremental updates for in the last few years. Can't wait for the Ultra version, though. I'm curious if it'll have a tiny M3LT style fresnel lens or something more like the current TIR optic.