The o.p. said they were a 'commuter'. My definition of a commuter is someone who is on the bike 3x/wk or more. I also assume that their one way trip from home to the worksite is 1mi - 3mi or more. I don't know of a high output headlight that wouldn't require fresh batteries every week and that just isn't environmentally condonable. I also agree that the top of helmet location is prime real estate for mounting a light to see with. It will have secondary benefit of making you seen but I really can't get down with all the fear of being hit. If that is your concern then take the bus! Nothing worse than a fearful cyclist working on their self fulfilling prophecy outcome. A cyclist is AS likely to hit something and be seriously injured or killed by that as they are of being hit and seriously injured or killed. Wouldn't it really suck to be so concerned about making yourself seen that you neglected the vital importance of being able to see well enough in the dark to avoid a deadly road hazard? I think so.