I'm extatic about the idea. Having a longitudinally mounted mid-engine it shares configuration with only a few elite relatives, Ferrari's, Lambo's, (a couple) Porsches, and a hand full of others. If I were building a locost or similar vehicle again, it would definitely be a mid-engined Subie.
IMHO the WRX is a fantastic choice because:
Very robust and reliable
Lots of salvage cars out there because SO many 'boy racers' buy then promptly wreck them
Awesome aftermarket support
Capable of huge power
Quirky boxer sound (personally I like the warble...)
Mid-engine RWD gives a low polar moment of inertia. (A terribly overused 'automotive journalist buzz word', but in this case, justified)
I'm also a fan of converting it over to a 2wd-rear. A decent 5 or 6 speed tranny for a longitudinal mounting position as most know, is hard to come by, and expensive. FFR had to partner and design a gearbox from scratch at substantial cost because there just aren't enough used 911 trannys out there to meet demand for their LS based GTM. - the WRX-middie has a built-in solution! And with a curb weight around 1800# one should be able to tweak the power up over 300 hp/ ft-lbs before having any problems.
If I were to build a subie-middie from scratch with a body it would cost me over $10k not including the thousands of hours of time.
In a couple years, I could see me selling the locost to buy one of these kits.
I can't wait to see what the winning body design looks like.
I've seen the FFR products in person at SEMA over the past few years and I'm impressed with the quality and focus on what makes it go fast as well as holding to their guns to keep the fit and finish reasonable.
Count me as a fan, and potential buyer!
-heck, maybe I'll get nuts and submit a design concept of my own. Maybe the winner will get a free kit.