I used to ride quite a bit at predawn.

There are 2 issues with lighting. The first is being seen by motorists and even pedestrians. The other is illumination of the road and its various hazards. If is sufficient street lighting on your route, you can easily get by with a system that merely alerts drivers of your existance. A front blinkie and 2 rear blinkies will generally show where you are. Oddly enough, if you ride in areas with a considerable amount of illuminated signage, you will need a bunch more lighting. It is easy for a rider to get lost in the dazzle. In a dark area, even modest lights make you stick out like a well beacon. If you need illumination, that comes at a higher price and is dependant on how fast you ride. If you ride over 20 mph, it is pretty easy to "out run" your head light. Even if you have a high powered light for illumination, I would strongly recommend having a blinkie on the front. A blinkie tends to attract notice of drivers more than a steady light.