I had the chance to directly compare my old TK20 to the light that supposedly replaced it, the LD25. The LD25 was brighter, but as always with LED lights in my experience, brightness is not always useful. The TK20 easily out-threw the LD25 and the XR-E in the TK20 was a warmer color than the XP-G in the LD25. That warmer color of the TK20 made colors come alive at night, while the cooler color of the LD25, while much better than a regular cool white LED, still washed out those same colors and made them appear lifeless and dull. Honestly, I'm not impressed by any XP-G lights and I have had zero urge to replace my XR-E powered ones with those with newer LEDs.
The LD25 was much lighter and more compact than the TK20, but it just didn't feel as good in my hands. The TK20 has some real beef to it that no other 2 AA powered light has. Honestly, it's tough to beat the TK20 in my opinion. It takes a beating and just keeps working. Plus, I love lights that are designed around the K.I.S.S. principle and the TK20 is a perfect example of that.