LOL, I laugh because I did the same thing, ripped the strap loop on the holder. The strap loops are quite a bit weaker than the loops for the actual light, so live and learn, but to anyone else I would be real careful trying to remove it, whatever you do don't pull on the strap loop- only use the actual loops that are around the light to pull on. You will know what I am talking about when you see it. I was not even intentionally pulling on that part but my grip slipped and my finger snagged the strap loop on the way. It would have been humorous at the time, had I not been wondering how much that was going to cost.
The body size is small (1xaa) and the tailcap looks like it is probably the same for all of them up to 18650, so it is quite large in diameter. If you are planing on putting this in and out of the headlight strap often, you might look for a different setup, as the factory one is not ideal for this. Hopefully they will improve on this. Anyone that has issues with this should send them some feedback, maybe they will pay attention.
The other slight annoyance was having to thread the head strap around in the different buckles, not a huge deal, but I have never purchased a headlight before where I had to do this, and I have had a few.
I do not know if the ZL mount will work but I ordered one, and will find out when I get it and my replacement light. Hopefully it will not be too long.