From what I understand, and this is strictly speculation, the engine is mounted lower and directly on, if not behind the line of the front axle. Which should make it's weight distrobution phenomenal! But I don't think there'll be a way for awd swap without throwing it way off.
Another AWD Subie coupe would be outstanding though, maybe it'll happen when they re do the wrx and sti in a couple of years. I love my awd but I'm not opposed to something that just spins the rears, especially if it's Subie powered! I believe it was you, Fuji, who said the ultimate handling mod for an sti was to by an s2000! LOL