hat NAO sure seems pretty fancy, but I'd bet a ZL H600 would leave it in the dust on any type of output/runtime/efficiency test - I'm also a manual/stick shift guy myself.
That's the thing. On paper and in the lab the NAO doesn't perform well, since if it gets locked into its highest output it does not last long.
However, in real use I have found the NAO plenty sufficient for week-long trips with plenty of battery to spare. The reason is because it is able to continually adjust its own output to the changing light needs and situation, so it's never running harder than it needs to.
In that same real life when I was using the Surefire Saint, and then the Zebralight, and then the Black Diamond Spot, I found myself having to reach up and touch the headlamp constantly. To spot. To check the map. To survey for landmarks. To hike a trail. It's tedious, time-consuming, and takes up precious mental capacity.
With the Zebralight I was constantly worried about leaving it in high mode and expending its laughably short runtime. With the Saint I needed a backup flashlight to get a bit more throw to find trail markers. With the Spot I needed to toggle it between flood and throw and then adjust output levels.
A breath of fresh air: with the NAO, I simply turn it on to one of the modes that I programmed in myself, out of 5 dynamic levels (and 5 manual mode, if I wish to override it), and I have both flood and throw, individually tuned, when I need it, without thinking about it. Each of the five dynamic levels select the maximum output and the percentage of energy each of the flood and throw LEDs are allowed to have.
I almost always put it one or two notches away from max, depending on the difficulty of the trail or speed of movement, and leave it the entire time. I don't have to worry about battery life. I don't have to worry about blinding myself. I can read a map without fiddling with my headlamp. I can see wild animals in the distance. I can find trail markers and landmarks with ease.
To me, the new Petzl Active Lighting system is the pinnacle. The NAO is the apex. It's a smooth, diffuse, sufficiently dim flood when I need it. It's a powerful burst of throw when I look ahead. It's everything in between, constantly adjusting, knowing before I know what I need.