I am biased. I instruct at several driving schools and, as an S2000 owner, I'm usually assigned to the S2000 clients. However, beyond the many S2000 clients, this season I've also done VW-R32, C-5, Z06, 911, 350Z, RSX-S and RX-8 clients.

FWIW, I can sum up my view this way. The RX-8 is a GT (grand touring) car that's nimble for a GT car. It's better on the highway than at the track (softer ride, amenities, etc). The S2000 is a sport-roadster. It's better on the track than on the highway (sport suspension, sparce amenities).