I was in London today and popped into Casino at lunch time and a had a couple of quick goes on AE and was owned by a guy playing Yun.
It looks like they just shoved AE into one of the existing SF4 cabs except it has 2 player controls rather than just 1. The player 1 just felt weird, like the joystick was in jelly but the player 2 side felt just fine. They have left Evil Ryu and Oni locked.
I actually played a bit of Hyper Street Fighter 2 and played against a couple of people, both friendly guys. One even little me use 2 of his credits, I felt bad when I beat him and he had ran out.