tatfiend 

I have tried a number of bicycle headlights and like a light bright enough to show the potholes in the streets in time to avoid them.

The Shimano dynamo headlight is a incandescent bulb and puts out a "to be seen by" light level in my experience. I have never seen a lumens or lux output listed but it is not much, 5 fireflies level maybe. Shimano uses a higher voltage rated lamp to keep it from blowing at high speeds but that decreases the light output at any normal bicycle speed. Too cheap apparently to put a voltage limiter circuit in their headlamp.

The Lumotec IQ Cyo I replaced it with is MUCH brighter and more effective and is an LED dynamo powered headlight. I believe it is in the 60 to 90 Lumens range but it has a well shaped beam with a vertical cutoff as is required in Germany. More effective lighting than I have seen from any approximately 100 Lumens claimed light output battery headlight I have tried or seen.

Light On! now has an American made dynamo headlight on the market for which they claim 350 Lumens light output, not bad for a 3W dynamo if accurate. I want to try it to compare with the IQ Cyo.

http://lightonlights.com/dynolight/

I have run a 600 lumens claimed output battery powered bicycle headlight myself with no adverse reaction from drivers so I believe that when properly aimed they do not find it objectionable.

If high power LED headlights on bikes do present a hazard to drivers or pedestrians then I suspect that we will see NHTSA, CPSC or DOT regulations on beam shapes and or maximum output allowed. 900 to 1200 Lumens bike LED headlights are now readily available if you want to spend the $$$.

As a motorist and bicyclist the headlights I find most objectionable are the HID lights now installed on some cars. They need a sharper cutoff to be less glaring to oncoming traffic IMO.