I decided after the two PB Blinky 3Hs' have died, being replaced once, that I am not going to put any lights on my helmet. I do wear a PB SuperFlash on my back, along with the rear tail light on my bike.
Once on my way back from a doctors' appointment, I came across a cyclist that had a vehicle headlight fashioned to his bike, with a battery pack. While I would love to be illuminated that well, it messes with the aerodynamics.