I have a 13W HID, but it's several years old and they dim over time, so it's actually only about as bright as my Magicshine LED.

Personally, I feel that the Magicshine is as bright as anything I need, and given two lights that both put out enough light, I'd pick the LED every time. HIDs start up slow, if they extinguish for some reason (hard bumps sometimes do it to me, probably because of the switch breaking contact), you have to turn them off then back on again and they take time to ramp up to full brightness.

At least, that's how mine works; it takes about 30 seconds to ramp up to full brightness. And while I guess some HIDs have multiple power settings, mine doesn't.

None of them have flash modes.

LEDs are more efficient, I think. My HID pumps out a lot more heat than my LED anyway, and more heat = less efficiency. Plus it has a much larger battery and no more runtime.

Given all that, unless you really need more light than an LED can deliver, I don't think there's any reason to go with HID. Even if you do, I'd probably go with multiple LEDs before I went to HID at this point.