Thx for your responses thus far. Any others, please feel to chime in.

I think I am starting to see the difference between helmet mounting the light, vs handle mounting it. Handle bar mounting it, focusing it lower towards the road like a car's headlight, has less chance of blinding oncoming drivers. If the light is worn on the helmet, say on a mtb trail, you don't have a road driver to blind.

I assume part of my thinking regarding the two places to mount the light is correct?