I'm not sure if these two do the same thing, but if the do, which is the better one? The Kaoss is about twice as expensive as the AirFX, so put that in concideration to.
Radiohead uses the Kaoss pad(s) live.
It samples (2 sec) and I think has more connection options.
It can also record finger movements as a patern...so you can warp a certain set of parameters and then warp another effect in the same way.
I did see Bjork's rythym section (2 dudes on a pair of Power Book Ti's) using the Air FX live.
I am interested in the Kaoss Pad.
I think you could get pretty creative with it.