Finally decided to sort out my lights and bought a1200 lumen Gloworm X2 light from Neninja for £130, included a £20 discount which is available until the 15th usinging code GLOWORM20.
Arrived within 48h of order which was great. Very small form factor and full range of fittings for both bar and helmet mount. Went out for a ride last night and used the helmet mount, pleasingly I didn't notice any extra weight at all but no surprise as it's very small.The light has several modes and out the box it comes ready for riding in trail mode. First impression was wide beam that extends well up the trail, very clean without any discernible hot spot. I switched between low and high for climbing / trail / descending and after a two hours ride the battery still showed full.
Not quite as bright as a friends big Exposure, but better spread and easily bright enough. Overall very pleased, well packaged and extremely proficient little unit. Will update as I go. If you're looking for a new unit I can highly recommend and if you have an questions let me know.