I have to be the world's biggest stick in the mud when it comes to rechargeable batteries! I've got a couple of Fenix-branded 18650s that came with a light and I almost never use it or them. But I did get a Petzl with a CORE pack, charges via micro-USB, and I like it very much! Run time isn't as good as with 3 x lithium AAA batteries but it's good enough especially since it's supposed to be able to be charged a couple hundred times. It does charge very slowly though.

Today though I took a pretty huge plunge! I just ordered a Cloud Defensive OWL weapon light that only uses 18650s. In fact, they state flatly that use of CR123a will void the warranty! At $369 it's a bit of a leap for an old rechargeable-hater like me but as an old IT instructor told me, "you gotta go with the new." Hopefully it lives up to the [considerable] hype.