Find something that is comfortable for you.
I prefer having a battery pack on the back of my head and a top strap. Any brick on the front of my head that isn't balalnced on the back is a problem.
If you hike steep terrain or plan to run with it, steer clear of the one strap models which will bounce around.
It sounds like you want a compact LED headlamp, right? I like having my thrower and close up light in one unit, so the BD Gemini and SuperNova are my favorites.
You probably want a small AAA battery lamp. The Moonlight, also by Black Diamond seems like a pretty good choice (but I don't own one myself). The PT Yukon seems like a pretty nice light, but I don't have one.
If you want to stay PrincetonTec, the Aurora might fit the bill. A bright, tightly focused light is not all that great for general hiking as it creates severe tunnel vision.
As for how much light you will need for hiking, one LED will usually sufice if you have a decent light in your group for occasional route finding. I would not want the weight and bulk of the Corona for hiking.
If the hiking is pretty simple and staight forward, all I bring along is a PT Scout. It is 1.8 grams, super small and sufficent for basic night tasks. Otherwise, I bring one of my incan&LED Black Diamond lights.