Seeing as we are on the subject of Zero wind/Ultra lights, I thought I'd put in my two-penn'th; with the caveat that this is not a review, just some thoughts.
At Hereford kite festival I got to fly the Absolute Zero (made by Peter Taylor of Airdynamics) for a second time.
Everything has been pared down on the kite to make it lightweight, including seams, so it is a single piece sail. Nevertheless I found it quite heavy to fly (but that could have been that it was soaked, along with everything else at Hereford that day), but it is a nice solid fly, & I managed my first (semi) successful 360 with it. It makes a nice precision kite, but as my tricks are limited, I can say that Peter tricks it with aplomb & Keith can make his own comments as he also flew it. In zero winds I can get kites to start axleing, but the Absolute Zero ended up floating gently on its back to the ground whilst I tried anything I could think of to stop it & failed.
All Airdynamics kites seem to come with a beautiful build quality (Thank you, Valerie) & are made to order, so custom comes as standard. This does mean there is always some lead time on kites though, 6 weeks is quoted on the website. Peter is very willing to assist flyers & advise & teach newbies, and to share kites.