You may want to look at the 2x400 setup Dinotte has on special. One on the handlebars and one on the helmet is hard to beat. You also have the safety of N+1 should one die (unlikely though). The beauty of the helmet light is that you can use it to track with - something I use extensively dodging critters and inattentive drivers.
I think I paid $350 for the two light setup.
And in response to the poster that said you need a screwdriver to remove them, it takes just a bit of ingenuity. A threaded stud and a wing nut solves that in an instant.