Hey guys, I too have been researching the HID/LED/H4 lighting issue for that last few years and here's what I came up with:
HIDs need to have the whole system (including wiring) built up and installed from scratch. If the "kit" you find is under $500, it is going to cause you headaches and hopefully no fires. Then there is the whole projector/hi beam/low beam focus motor issue. Also it isn't safe or worth your time to "retrofit" your H4 lenses with HID bulbs, unless you can live without high beams and don't mind not having good focused light so you can actually see what's ahead. Sure it looks cool, but the actual system is trouble.
I have seen many LED lights, but they aren't truly dialed in yet, wait for better focusing and the technology to increase.
I have chosen the Cibie H4 lighting for my truck, the engineering that went into these lamps is second to none on the road right now. (unless you find some of their older and much more expensive predecessors) The reflectors are designed with quality and precision beam placement, which enables you to see better. Their light is cast where it needs to go, the "hot spot" is down range and slightly to the right and with an off-tick to the upper right to illuminate street signs. I was thinking about using Hellas again like I used in my Mustang, but their beam is not as focused and since my truck goes down dark dirt roads etc, I want as much light as I can have. Besides, H4 bulbs are $7 ea., so I can have 2 extras ALL the time.
Just my