The AODE would probably be cheaper in the long run. A T-5 needs a lot of internal swaps to handle that kind of power reliably. If you wanted a 5 speed transmission for an 11 second car, then the reasonable choice would be a Tremec 3550 style transmission, which is going to be at least $2K by the time you get a clutch and all the swap parts. Even more money if you want a decent 3550 transmission. You can get a really hefty AODE for that money, and with the right setup it's going to be just as fast as the 5 speed. It just won't have the same street manners. The biggest factor is in how you want to make that 400hp.
Kurt