Red__Zed

I actually just went with a regular WRX. Bought it to DD instead of the Z, and they just about split driving time while I owned them both.

I think living where I lived then, I'd have skipped the Z and gone straight for the subie if I could do it again. The Z is a great car, but the WRX/STI is on the same plane of performance, without most of the compromises present in the Z.
There's no replicating the feeling of RWD, but the WRX is usable in all weather, which more than makes up for it for those of us that live in places with seasons.

Quick thoughts--

The WRX is much torquier, and feels quicker around town. There's just more power down low the powerband-- even without a tune.
It doesn't have the high-end scream of the Zed, but for a road car, I prefer the torque.

The trans is the WRX is an old school 5 speed, which is kinda lame. The STI trans is smoother than the Z's though. Both are pretty strong transmissions.

Dynamic-- the Subie's understeer A TON-- even more than the Z does. Potentially annoying, fixable by a rear sway. If it didn't bother you in the Z, it won't bother you much here though.
The Subie's feel lighter, mostly due to the steering ratio. I feel like I'm in better control of the car on tight courses, and it definitely autocrosses faster on most courses, even with skinnier tires.

Brakes-- wrx brakes are lame now. STI brakes are solid. I'd put them about equal to the akebonos.

Anything specific you want to know, just ask.