I would imagine having a helmet light would be very helpful for illumination compared to a static handlebar light, in fact just been looking at the 'P7' and 'Fenix' torches for mounting, but I'm still not convinced that if I was to come off or get hit, having something mounted, would surely cause some kind of problem, whether it is the mounted element being smashed in to your head, or if it doesn't break off or doesn't break off quicker enough, and I don't know, for example, if one comes off and rolls the mounted element would stop you from rolling naturally
surely that would result in a nasty head jury.