Speaking of which, I finally got my IQ Fly N Plus, or the model with the standlight, driven by the Sturmey XFDD dynamo drum.

Very bright, but not as bright as my Cree Q5 flashlight driven by an 18650 lithium battery.

My guess is they're driving the LED at the hubs 500mA, providing 1.5w of output from the LED. Given the lack of appreciable heatsinking, it makes sense that they've not gone for more than 1.5w. My estimate is about 100 lumens, which for all practical purposes makes it an ideal light for urban riding on the road.

For off-road use, a conventional round reflector would be better at lighting up the branches around the trail.