From what I've seen on the track, the Evo seems to be better balanced than the STI out of the box. The STI "looks" a little top heavy and leans a bit much. The Evo seems to perform a little better in the handling department. If you want to get into AutoX & road racing events, you might have more fun with the Evo.
If you want the hp advantage, obviously get the STI. No replacement for displacement, even with turbo. Otherwise, if its going to be your daily driver, get the WRX and be happy with it.
