I've never used an LED conversion but I am not sure how well an LED bulb would work in a housing meant for an HID bulb. It has to do with how light is reflected and refracted. HID bulbs give off light in all directions whereas an LED might not hit all the angles and either give too much or too little in some areas. True LED headlights are built very different so I'd have to say while it's cool, it might not work the greatest.
Aside from that, LEDs produce heat that needs to be dissipated directly from the LED and not through the air inside the headlight just like incandescent or HID bulb. This kit uses a heatsink and a fan to cool the LED. Now the question remains how long will that fan last. Does it hold up to sand, dirt, salt (if in salt belt) and for how long. What happens if the fan gets stuck from debris? does it turn off or does it burnout. If the bulb burns, what's their warranty and can you buy a new one or a set, how much is that?
I've personally just upgraded to better HID bulbs as I get away from having to worry about what I mentioned above.
In terms of accessing the ballast to install this kit, you'll need to swap the ballast (round puck looking thing) and the bulb. First you have to remove your airboxes completely.
Here's a video showing the ballast being replaced:
Replacing Ballast