Thinking about this thread and general lighting issues, I am coming to the conclusion that for traffic use, 600 to maybe 1000 real lumens is an appropriate (perhaps even a bit high, especially at 1000) limit for symmetrical beam lighting. The actual limit is dependent on beam angle and aiming of the lights, properly expressed as lux above horizon or similar.

If, on the other hand, you run a properly shaped beam, feel free to generate and and emit just about as many properly placed lumens as strikes your fancy. Last I checked, excess here is still prohibitively expensive and heavy for bicycle use, though at some point a line may need to be drawn.

Tor