If anyone's interested I slapped together a new light head using the 7up XML board + optics sold at:
I used 3 * RCD-24 1000ma drivers in parallel, powered by two 4S Turnigy Nano-tech 3300mah lipo blocks in series (total 29.6v). I had the batteries lying around from another solution, otherwise would have used something bigger. Burn time was 57min before the light began to flicker, which the RCD drivers tend to do when battery is flat.
Although a pain to get the voltage high enough, this head puts out a serious amount of light and seems to have a lot of punch. The optic in practice produces a ~25 degree beam underwater through a flat 5mm acrylic lens on the housing. My buddy was using an XML triple Cute3 at 2400ma on the same dive, which was largely overwhelmed by the 7up with a wider and very dense beam of light. The Cute3 spot was still a little brighter though when it hit the subject.
I had a gopro mounted on a helmet during the dive, so will upload the footage if anyone is intertested. Was a woeful dive though and wideo isn't any better, poor vis and cold!
No surprisingly this setup produces a lot of heat, though wasn't a problem underwater. I used thermal grease under the board, which is just held against the alloy heatsink/housing by the optic and front lens.
Watt meter reading, wattage jumped between 69.1-70.2w.