I disagree with the drawbacks in this ability. This ability is supposed to be extremely strong. It is the equivalent of water bender's blood bending, something incredibly strong. It's also another equivalent of Sozin's Comet, the incredible power that a fire bender gains.
I see a lot of things being said about airbenders losing their flight after being hit. I disagree. In Zaheer vs Korra, Korra manages to hit Zaheer with some Ice, but although yes he does descend, he does not lose flight entirely. He quickly regains flight and swoops away at incredible speeds.
Zaheer vs Korra, Zaheer is seen flying at incredible speeds, so I think this ability should be incredibly fast. Actually, I think there should be a way for an air bender to change the pace that she/he is going. I think this ability should be activated with left click. The airbender could then tap shift with airbender flight still selected and their flying speed will be increased. Tap shift again, another speed increase. Tap shift again, and another speed increase and so on.
I'm gonna contradict my self a little bit here, but even though I did say there shouldn't be any drawbacks, I think there should be an option in the configuration, similar to blood bending: how it's possible to make it so blood bending only works during night/full moon. I think it should be possible to make it so this ability only works if the user's inventory is empty, to signify that they are literally, not attached to the earthly tether, as they hold onto nothing, no materials, no possessions, no nothing.