i have tried intelXDK the first time these days. It's really simple to get your App to work in the XDK and you can easily run it on iOS Devices with AppLab. But I haven't found out yet how i can export my project to an IPA which i can really test locally on an iDevice with Xcodes' test deployment. I don't know if this is even possible.
to answer your question: i haven't tried CocoonJS yet but if I won't find out about the realtime test deployment soon, i will try to do it with Ludei's Cocoon JS and inform you about my experiences.
ah by the way .. when i was compiling my game with appLab i didn't notice a big difference in performance ..
I gotta say that both look very serious. I got a bit shocked of appMobi because of all that Credit Card stuff. Don't what's that all about. aditionally Ludei is about to provide 3D support which is reeeally cool though..