I have a feeling that in a few years we are going to start seeing regulations about these things. The problem is the point source. While they may not flood the road like high beams do, the attempt to do so creates an even brighter blinding source. How long will it be before some cyclists get pulled over for not dimming their lights for oncoming traffic?

Flash modes are also going to be a problem. The reaction I got one time was "I thought a friggin freight train was coming at me", and I was on a sidewalk path (legally). My light isn't nearly as bright as yours, just a Chinese flashlight with an XML-U2 LED, bright but not 1800 lumens. I use it on the low setting now and it is still brighter than most of the other lights I see, which are mostly Planet Bike.