The thing is; that goes for the both of you. Being airborne with your opponent is a double-edged sword. Or, that is, it can be if you're not careful.The most notable pattern or similiarity in all or the majority of EIG techniques is that they put the opponent airbone, it's always launch into the air, and deal the finishing blow from above into the ground. Most of the EIG attacks Gai and Lee have used throughout the series also involves them being in the air along with their opponents, needless to say that doesn't mean EIG is an airbone combat style, it simply means that it puts the user at a greater advantage. As the target loses footing and balance, while unable to see the user.
Being airborne with the Gates open means you'll have very few options to manoeuvre properly. Your opponent might have some fancy CJ that allows him to walk on air, quickly back on the ground, etc, but you are going to have a hard time getting back on the ground within a reasonable timeframe.
Can it be a good move to your opponent airborne? Perhaps. Is it something I would do? No. Here's why: the fact that you punch/kick your opponent into the air should be enough to end the fight. Period. If the opponent allows such a direct hit to connect he should be punished most severely. This isn't the Naruto anime. Bio's aren't made of rubber. If you're hit by a guy who has even just one Gate open you're going to suffer some real damage.
All in all I would say that being airborne puts you at a disadvantage across the board. It might look cool in the anime and sound cool in the description, but that doesn't mean that the move is practical. There are too many variables in my opinion.