I was just curious about the actual usability of this light. It's very small and is only reporting 20 lumens of output, but reviews from Rei.com say its a great, small, be seen light. Does anybody have any experience with this light in either day or night visibility to others? I do already have a very powerful headlamp with a battery pack so this would be for commuting in the day and on lit streets at night/dusk or cloudy weather. Thanks!