You might want to move this thread to "Automotive." There's a lot of discussion there, including good knowledge of what is legal and what is not.
In general, changing the type of light source (incandescent to HID or incandescent to LED) is never legal. As a motorcyclist, I know we sometimes get away with a bit more than do automobiles. And I certainly have an interest in being visible. But this particular forum is VERY strict about never advocating anything illegal. Just a word to the wise.
For what it's worth from the research standpoint: Even before I got the word about legality, I was looking into LED replacement bulbs for my motorcycle. I found that most of the LED bulbs for sale used a lot less power but actually put out less light. The only bulb that seemed to put out more light was an LED cluster so big that I'd have to do major surgery to my reflectors to get it in. Also, LED bulbs (and this matches my experience with LED indicator bulbs in the control room at work) tend to be more directional than the incandescents they replace. So if you are in line with the light, it seems very bright (annoyingly so for some of my indicators), but get off to the side a bit and you are suddenly not getting enough light. I guess that's the reason it's illegal to change the light source in a lamp.
But there is a great selection of LED lights available today. Most of the "names" in trucks and trailers, such as Grote, Dietz, etc. offer LED lights of all sorts. For a quick sample, there's a wrecker and service truck supply outfit called A&W Direct (go to
www.awdirect.com ) that offers quite a bit of that stuff and they ship quickly. I'm thinking to stick with my stock taillight bulbs, but maybe add a couple of LED running lights on my hard bags (use a quick-connect, because my bags are detachable) to increase my rear visibility.
In front, I have standard wattage Phillips Xtreme Power H4 bulbs (next time, I'll get Xtreme Vision) in the headlights. I'm going to upgrade to heavier wiring with relays, but stay with stock wattage. I believe I can just barely carry a pair of Soltek Fuego HID driving lights with my high beam, and a pair of yellow Cibie H2 fog lamps with low. Big white headlights top center, and yellow lights as low and wide as possible, should give a nice contrasting "triangle of safety" from the front.
One thing about LED's, they really don't take much power. Bikes have small charging systems. One could add side markers and use very little power.