So with two 100 milers coming up this summer, I thought it would probably be a good investment to purchase an actual trail running headlamp. Over the years, I've religiously used the Petzl Zipka for all of my hiking adventures. It is still in my opinion the lightest, most efficient, long distance hiking headlamp around. The batteries last forever, and it provides ample light for night-hiking (although I only really night-hiked a few times). I have carried my zipka for almost 3000 miles of hiking and it has never failed me.
With that being said however, I find the Petzl Zipka inadequate when it comes to night time trail running. It just doesn't show you enough of the trail up ahead to feel confident that you are not going fall face flat onto some pointy rocks. So, I did some research and managed to find the Petzl MYO RXP. This is a new model from Petzl that's marketed just for ultrarunners. It was a little pricey (although on sale at EMS), but I figure it will be worth it. I haven't had a solid test yet (plan on doing tonight), but as far as lumens go, it is over 4x as bright as the zipka in its brightest mode. It also features 10 different lighting levels, a wide-angle and focus beam setting, is compatible with Lithium batteries, and has a Boost switch (that gives you 20 seconds of 160 lumen powered awesomeness!). The only downside is that it is a bit heavy with a battery pack at the back of the head. It does come with an additional "over the head" strap that keeps it in place though.
Petzl Myo RXP
Max Power Awesomeness!