I think we just recently had a thread here about this. Other than the fact that HIDs don't like to be switched on and off - it shortens the life, and they don't achieve full brightness for a couple of seconds. If I got my hands on a dual headlight setup, I'd probably look into converting it to LEDs. But I'm an LED junkie now - every bulb, including the headlight, on my bike is now LED. (Well, as soon as I get around to replacing the license plate light)