I am not directly answering your question, but as a user of both a dynamo light system and a 500 lumen USB recharable headlight, I will offer some thoughts.

Dynamo systems cost more money -- the dynamo itself, and generally the lights cost more. More expensive, new models of dynamo lights are very bright, topping 1,000 lumens, I believe.

I own a Lumotec IQ Fly Plus light, dynamo-powered light, which is about 500 lumens, and I own a very inexpensive Cycle Torch Shark 500 USB recharable LED light that is also 500 lumens. The LUX measurement, if I understand correctly, is a better figure to use, since lux takes into account how the lumens are spread ahead of you. A pinpoint of 1,000 lumens is far less useful than 500 lumens spread specifically on the area you need to illuminate.

Anyway, the which-is-brighter question is not very applicable anymore, with the LED dynamo driven lights at the crazy bright zone already. The question you need to ask is if it makes sense for you to build up a front wheel with a dynamo hub, which can be expensive (do yourself a favor and save money on the wonderful Shutter Precision line of dynamo hubs), and then buying what is probably a more expensive dynamo powered light compared to a battery light.

For my touring bike, I have a dynamo hub with the Lumotec light. No worries about batteries dying or recharging. For my single-speed commuter, on its short rides to and from work, I use the cheap Cycle Torch Shark rechargable. Both those lights put out the same lumens and approximately the same lux. They are perfect for illuminating totally dark roads. I just did not want to add the weight and expense of a dynamo system for my single speed commuter, and bought the cheap Cycle Torch Shark light. Theft is also a potential problem with my commuter. I did not want an attractive dynamo hub left out on the bike rack, or the installed dynamo light. The recharagable cycle torch shark pops right off from its rubber band mount.

Follow up with more questions, since I did not directly address your specific questions but instead just gave you some insight into why I chose one system for one bike and another system for my commuter.