Well...I guess at my age, I'd be more than happy with your A2A setup. I just don't like the torque curves with turbos, which is why I'm going s/c, and want an enjoyable, reliable, fun car. e85 isn't readily available in my area. If I do go with the 928 build after a few miles on the Si, I wouldn't boost pressures higher, and keep them at ~9psi. I'd like to see what others experience with the 928, and if it really provides noticeable and earlier torque.
I'd also probably have a difficult time convincing the wife that putting more money into the car will reap huge rewards!