^^^ Yeah, true. There are some ridiculously bright dyno lights now, and even though they can come with a "standlight" circuit (stays lit for a little while after the wheel stops turning, so you're still lit up at a stoplight), it points where the bike points instead of where your head's pointed.

Considering that, and the fact that my road bike doesn't have a dynohub, there's one helmet-mounted battery system that I've had for about a year -- a Light & Motion Vis 360. Easy to take on and off, easy to charge, well-balanced, and I'm sure that I'd have to charge it more than once every few months if my commute was longer.