I've been using them for six years in a Streamlight Polytac. They work just fine but that is only a 275 lumen light.
I sometimes wonder if they might be just as good as any thing else out there. I figured that if they didn't last as long as the Streamlight batteries I would just change them more often, they are half price but they do last as long if not longer.
I think that SelfBuilt's testing of them and the Panasonic derivatives, found that the PTC safety kicked in at a slightly higher temperature than the Pannies, which might be 'more' problematic in today's lights, with higher outputs.
Aren't these the batteries that had all them huge problems awhile back. Don't remember the details but it was a huge problem With them but again not real sure.