At SHOT show last year, I discovered that Streamlight's new TLR 9 WML could fit the 16650 rechargeable battery in my EDC flashlight. The guys at the Streamlight booth didn't know that, and nothing I've seen from Streamlight shows that they even realize they've created a great, rechargeable capable WML.
I recently snagged a TLR 9, and so far I'm pretty impressed.
TLR 9 w/ 16650 = 128.1g / 4.52oz
I had been concerned that the use of a 4.2v battery would drop the brightness vs the 6v 2XCR123, but if it has I haven't noticed it. The light is plenty bright running the 16650.
7 yards night:
7 yards TLR 9:
50 yards night:
50 yards TLR 9 (slide removed from frame for this pic):
Overall I'm pleased. By being able to use rechargeable batteries, I can get a lot more use practicing with the light, as well as making the light more useful for just shooting at night / in poorly lit indoor ranges. With CR123 lights, I was always hesitant to turn them on, as each little activation lowered the overall charge in the light.