you know the co2 is medium ar and the spectrum more High ar. It would be hard to compare the two.
Not true. The Co2 is mid-high aspect. I you can hardly tell the difference between the Co2 and the nitro. The spectrum 2 is hard to classify because the aspect ratio changes with the size of the kite, they call it C.A.R. The spectrum 2 isn't a high AR kite like the X4 or Rhino2 & Rhino04.
I haven't ridden either kite, but I have seen them on the beach some. The 05 C02 is supposed to be a great kite. They aren't even making the Nitro next year.