In reply to Duncan_S: Have you tried halogen/xenon bulbs in poor visibility (mist and cloud)? They work fine. Then try the LED lights in the same poor visibility and the light bounces back.
For LED torches, I've used the Tikka and Myo XP in both good conditions and in misty conditions; for halogen, the Zoom. In good conditions, there is no problem and the Myo XP is a fantastic torch. However, there is a significant drop-off in the usefulness of the light in poor conditions compared to the good old halogen/xenon bulb.
I would also consider the BD range of headtorches too.