Re: BlackDiamond Storm vs Zebralight H51 series
The Storm and other traditional headlamps do have a few advantages:
Being a little bit longer, they protrude better from under a brim or visor, which is excellent when it's raining. With shorter headlamps I find the beam gets cut off by the hood.
The unregulated runtime tail gives you more than ample warning to replace your batteries, often on the order of days' worth of use. Sometimes it is not practical or convenient to replace your batteries right away.
Having both flood and throw in a single light is very convenient and not overrated at all. On some hikes I may wish to use the throw, others may be better with flood. If you need to spot trail markers in the distance or look for landmarks further away, you'll wish you had some throw. For walking in wide fields or open terrain, flood is preferable to reduce eyestrain. In either case, when setting up camp, throw is excellent when hanging a bear bag but flood is better for everything else, especially reading.
Red mode is undeniably useful as an outdoorsman. It attracts less bugs, is less visible to wildlife, and disturbs other hikers less when you walk through their campsites at night. It's also great if you're trying to see by moonlight and need to preserve your vision but need to check something that requires illumination.
In the Petzl Tikka2 models (I like the XP2), you can effectively change the batteries underwater or in heavy rain. The battery compartment isn't sealed but the electronics are, which means there's no downside to opening the compartment when wet. For what its worth, I prefer the XP2 over the Storm because it's lighter, has an optional rechargeable battery pack, and is simpler to operate.
Personally I find the silicone holder of the Zebralight less comfortable than that of the Black Diamond against my head.