In reply to the sheep:
Apologies for ignoring the question and offering unsolicited advice instead, but...
Whatever head torch you end up with, can I suggest that you also have one in your hand?
The trouble with a head torch is that the beam being very close to your eyes kind of 'flattens' what you see, which can be less than helpful on awkward terrain.
Also, this, from the post above^
> Only downside is in thick fog (as for all head torches)....
Aimed at the ground in front of you, the beam passes right in front of your eyes, so if there's a bit of fog there you're dazzled by the brilliantly lit droplets of water. I find it doesn't need fog for this to happen, if it's chilly and I'm working up a bit of a sweat then just high humidity will do - unfortunately I manufacture my own fog! Any time I can see my breath, a head torch on my actual head is not very helpful. (And this is usually the case on a clear night from now until the Spring.)
What I've taken to doing is having a relatively feeble cheapy Decathlon head torch with a wide beam mounted on my chest - that's just enough to see where the path is when the terrain is easy, doesn't wreck my night vision and does fine on familiar ground when I know where I'm going. (I don't run very fast at the best of times anyway, so it doesn't have to light the path v far ahead.)
Then I also carry a more powerful torch in my hand - used on low power for more tricky terrain over rocks/roots etc. and high power as required for navigation or whatever.