It is very hard to get an accurate idea, which is why I figure I'm just going to have to buy it and find out . Even if it doesn't end up being bright enough to make me happy I will probably keep the bar mounted part and replace the helmet mount with a HID. Now that will be bright .10-15% of light is a big difference... seems like a very abritrary measurement (with all due respect to the guy... )
Weight not that different? The ayup weighs 200gr with a 3 hour burn time. The lightest HID I know of is the vicious power, at 400gr with 2.5 hour burn time. As to the price, the $350 quoted doesn't include tax, presumably making it $385 before postage. A HID technologies light (5.5 hour burn time, 500gr total weight) costs $425. So (in my eyes anyway) the only major advantage of the ayup is the weight, with the disadvantages being lower light output and longer charge time (12 hours to charge the three batteries fully, compare that to 3 hours for the HID).The combined weight of the ayup's is not that indifferent to a high end HID, but the (current) price is half, that's pretty compelling.
I like it. Both battery and head unit are light enough that when you add them together you still have less weight on your helmet than almost every other light on the market (the only one I can think of that is lighter is the Vicious I mentined earlier).I'm not so sure about the battery-on-helmet arrangement, but the website talks about an extension cable so I'm sure that'd be sorted easily.
After comparing it side by side like that to the HID techonologies light, I think I've changed my mind on the ay up. If I could get just the bar mounted unit with one small battery and a charger for about half the price I'd go for it (to run in addition to a helmet mounted HID) but given it's short comings and no real price advantage, I think I might have to go to the HID instead.