For nighttime use the 400L on high is far too bright. I put my bike next to my car at night, and the brightness of the light overwhelmed the brightness of the taillight.
One of my reasons for getting the 400L is that I commute east in the morning and west in the evening, often into the rising / setting sun. So the competing light source is the sun, which I must admit is significantly brighter than the Dinotte 400L on high. I've put the bike outside in the bright sun, and the light is still visible, so I think it is reasonable.