I have found LEDS to be expensive, and occasionally unreliable - sudden failure and needing replacement. they also need to be correct polarity for the bike, which would mean keeping spare globes in positive AND negative earth.
My 6V systems are on a par with 12V for brightness, and the globes seldom fail.
I fit a relay in the headlight shell, for the headlight globe, and run a separate earth for the headlight and tail light back to the battery earth (at the frame).
I also use a Quartz Halogen headlight bulb.
Richard