I always run a sold light AND a blinking light. The problem with just a blinking light is that it give no indication of speed or direction. That's useful information for other bikes and motorists to know.

My sold light might be as bright as I need it for seeing on a dark, unlit road. My blinking light is a 1/2 watt cateye.

I would NEVER put anything bigger than a half-watt light on my helmet. My bars generally remain pointed at the road. But my head goes all over the place. I often look direct at motorists. The last thing I want to do is blind them.