True. When I was just starting to move from NiMH to LiIon as my primary lights I did worry about that, and the batteries weren’t as good then either. I think using LiFePO4 cells in a D4 or similar would be safer for a “muggle” using the light, and could take away some of the worries they might otherwise have, and regarding the heat issue as well. It would probably also drive less current through the light should the battery be reversed.

With my 219B D4 mod, not wanting to inadvertently damage the glorious LEDs I might somehow mark the light “LiFePO4” or something like that.