As Jon says, I have the STD and the UL. I bought the UL nearly two years ago and loved it, it gives away backspins and opened up some stuff I hadn't got before. Back then the STD was more expensive and I could never justify getting one so moved onto sevens. For some reason I find the UL frustrating to fly now and prefer my Seven UL. The ophidion UL will fly in very low winds tho' and I think that if I stuck with it for some time I would be able to get everything I want out of it.
Custom made Kites have only just started remaking the STD and I bought one first chance I got. The STD is a very nice kite, well made and a capable freestyle kite. As Jon says it is very light on the lines and It has got a very broad wind range and copes well with higher winds but flys best below about 12mph.
I like my Ophidions, but that said I am thinking about selling them in favour of something with better precision and square corners. So if you are interested let me know