There is some thermal path over thin copper layer on the PCB you can see on the picture. Those small triangles then lay on the housing. I should make a picture. Take a look to the pictures made by Garry on very same constructed light, just different driver. There is also some thermal transfer via two screws. PCB is 2mm thick, a little bit more than tipical ones.
The power used is just enough for that small light. Better heat transfer would help of course. As far as is being used as helmet light, there is just enough light if you are using some more powerfull on the bars.