Personally, i didnt notice any advantage in flying stoned. I enjoy it a lot more smoking after fly, and not before.

I do sky dive and paraglaiding (this more often), and i know many guys who always take off stoned, and sincerly, for me is no sense. Flying feelings are enough strong.

And one of the guys always flies stoned died in front of me: start making acrobatics very near the ground, ignoring all the people shouting him to stop, and finally crashed.

I prefer having all my senses at full power when flying.