Supernova claim that this is "the brightest HID outdoor lighting system available", and it certainly outshines anything else I've ever seen.
With two 14W HID bulbs - the equivalent of 100W of halogen power - the Supernova emits the same amount of light that you'd expect from a small car. In fact, the beam is unnervingly bright - almost embarrassingly so when overtaking other riders - and cars give you plenty of room, probably assuming that you're a motorbike.
Off-road they scare sheep and walkers alike with their helicopter-searchlight-like intensity. They're incredible. But not as incredible as the price. Nearly eight hundred quid? You could probably rustle up some sort of GoldenEye space-based solar reflector to pipe daylight onto your path for that sort of money. Or, more realistically, you could buy a Lumicycle twin HID system. With a bigger battery. And a spare battery. And a spare HID head. And still have enough left over for a decent backup light... and the bus home.