I have an L&M ARC HID. I only have the NiMH battery so run time is only 3.5 hours on the low setting. The biggest Lithium battery will give you 6 hours on low. One reason I bought it is because it can be a handlebar mount or a helmet light. Seems the overwhelming number of mountain bike riders say you have to put your main light source on your helmet so the beam is always pointed where your eyes are aimed. For really fast or technical riding, you need to put a light in both places. For the simple flatland riding we're doing around here, I added a Cateye EL400 to my hemet just for a backup. When I do any night time trail riding, I'll switch. My bike goes where my head goes so I want the light to do the same thing.

Hubby bought a NiteRider Dual Classic because it has two beams and puts out a ton of light. The newer version has scaled down the size of both the light and the battery so it could be out on a helmet. This light is not an HID and I have to say I prefer the HID bulb in mine. I see better detail with it.