I use two Niterider light systems, one light mounted on helmet and the other on handlebars. The NR Evolution which is a simple 10w head is twice as bright as the fancy 15w, 10w or 6w digital out of the box which costs almost twice as much. I switched batteries to see if that was the problem, it wasn't.
Has anyone else experienced problems with the digital models? I'm not impressed with them. I'm thinking of exchanging the digital 15w model for another non-digital and changing the 10w bulb to 15w.