I have multiple bikes & several lighting systems: rechargable battery powered 10watt & 15watt halogen bar lights, a 3watt LumoTec Oval+ light driven by a Sturmey Archer Dyno Hub, a 3watt halogen light driven by a Soubitez bottom bracket generator and a 3watt halogen light driven by a Union sidewall generator. The 10 & 15 watt systems provide much more & brighter light with better visibility than the 3 watt systems, especially above 20 mph but as others have said, battery charging is a nuisance. But the 3watt systems are definitely an improvement over a 5 led blinker & give acceptable light on a dark road if I respect a 15 to 18mph limit. Higher speeds are risky without more light or bright streetlights. I took a fall this Winter when my 15watt light went out unexpectedly on a dark country road. I was fiddling with the cable trying to get it working again & veered off the pavement edge, then fell. In my experience, combining a hub generator light with a battery powered halogen light is the best solution. My favorite combination is the 10watt battery system for long run times along with one of the generator systems to give a wide & focused lit area plus some redundancy if one system fails. Also the LumoTec & some generator systems have overvoltage protection to protect the bulb on high speed descents. Don