Uneven loading on ac generator.

As some know I'm working on some pushbike cycle lights.

My front and rear leds allthough the same wattage are different forward voltages, to get both on together at the same brightness I thought of effectively reverse paralleling (through fet switches) across the ac (I know there are other ways of doing this, but this is simple).
This means the ac waveform will be unbalanced, 10.6v upper and 8v lower.
What kind of effect will this have on the dynamo, I'm suspecting increased heating and possibly causing remanence in the iron lamination core, the latter being the main concern.

asymmetrical loading shouldn't bother most generators, regardless of the size because of the large air gap in the system. (in this case, neodymium or ceramic magnets)

I agree, I can't see any problems whatsoever.

I'll give it a try then.