The Acebeam looks nice! My main complaint with the HD12 is that it is kind of heavy, 48g without the battery or strap. More like 90g including everything. The Acebeam is lighter, and if you want just a flashlight instead of a headlamp, the Skilhunt E2A is quite light.

For headlamps the Nitecore HA11 (mentioned) and HA15 (not sure what the significant differences are) are the lightest out there. The HD15 is a few grams heavier than the HA11.

Acebeam H40 also looks interesting.