I rode round the red route at Glentress last Wednesday night with my new diablo torch on my head and i thought it was really good - used the low setting on the climbs and high everywhere else - out for about 2.5 hours (few goes at spooky wood) and it showed no sign of letting up.
My mate had a few year old exposure light which mine was notably more powerful than on full, plus the exposure helmet mount was better than his tie wrap to the helmet solution. The diablo is really good on your head you cant feel its even there, and the button is dead easy to locate and operate with gloves on.
Saw a few other people out with various lights none seemed to make mine look underpowered, so all in, I was impressed!
I will state again though - I have zero previous experience of lights or riding at night!!!!