Hmm, growing wings... interesting. But I would look like that worm on "A Bugs Life" movie when he turns into a pretty butterfly. My wings would be so small, I would have 2 feathers on each.
I personnaly hope that both sides would be able to fly. I recall seeing the newest trailor with people fighting in mid air with their wings out... unless I just looked at it wrong?
I hope both partys have wings, as someone stated earlier... I would feel a bit odd being this big old ugly bad guy (the fallen) looking up at my enemy. Kinda of a disadvantage I would think? Maybe the evil side will have demon/dragon type wings? They did say there were going to be dragons in Aion.
And I would think that we would be weaker with the wings on. An example would be City of Heroes. You use more Endurance/Rest in the air, so you are unable to use many of your powers... otherwise, you become tired and fall to the ground. And we already know by the Aion movies that you do get hurt when you fall.
I could go on and on.... I tend to babble, sorry all. You will learn that about me.