The B&M Ixon IQ Premium puts out 80 lux for 5 hours or 15 lux for 20 hours. The Edelux II puts out 100 lux, so the battery powered light is a little less bright but totally adequate. When I need more than 5 hours of lighting I leave the light on low except for descents and pack an extra set or two of batteries. I've ridden a lot of miles in the dark with 15 lux and it's fine for me. I've ridden GR's with both dynamo and battery lighting and there are pros and cons either way. As I mentioned, I decided not to put dynamo lighting on the bike I got last season having ridden the last several seasons with a dynamo.