In a race with decent conditions the S2000 will win in stock form. Its just that simple.
Let the conditions get wet and/or traction limited in whatever way, and the WRX walks all over the S2000.
The WRX is "easier" to drive at 98%. The S2000 can get twitchy at the limit if you dont know how to drive it correctly. But with equal GOOD drivers, the S2000 wins.
the WRX has a few advantages...
1) practicality...its a 4 door, small, but its going to seat twice as many people.
2) mid-range power... on the street, you dont need to be revving the thing to redline to pass people. Its got good "emuf" from pretty low.
3) Insurance, im young, lots of people on this board are too....it matters.
4) Saftey. WRX has a roof, nuff said. Its also easier to get out of trouble with on the roads, and its heavier, meaning it has an advantage over a S2000 in an accident.
5) Upgradeability. Get rid of the 3 cats, and open up the intake, and give it some more boost. Easy 12s. You cant do that with a S2000, sorry.
The cars are different, figure out what kind of car you need, and buy accordingly.