I see no requirement to have a regulator in led circuit driven by a dyno because dynos never exceed the current ratings of available power LEDs. If you want to have a lot of low-power leds in an array, you can always parallel them to handle the current. A regulator would just waste power. I think the most active any modern generator light gets is switching the input circuit from a voltage doubler to a straight pass-through circuit. My Supernova does this in a fairly obvious way when cresting a hill. Haven't noticed it with the B&M Lyt, but I don't usually get going that fast with that bike. I have seen discussion of using an active circuit for improved low-speed use. It would also be nice to be able to dim the lights, but I don't know if I would actually do that in practice.