I would keep the S2000! Everyone that sells theirs always regrets it!
Up until a couple weeks ago I had 2 S2000s. One setup for the track and my original 2001 S2000 that I've owned since 2006. I will never get rid of it and it perfectly complements the F80 I recently picked up. My S2000 is supercharged and makes about 400whp and while it's probably slower than my F80 ZCP it is so much more engaging to drive, and erases the issue I had with my S2000 when it was stock - lack of power. If you have mechanical skills, putting in a supercharger really complements the car and doesn't change the power delivery; it just multiplies it. You get one of the best gear shifters in the business with a really nimble chassis that can be really satisfying to drive. It will still be really reliable if you keep it under 400whp too.
Here's some pics of the two S2000's i had. One was a hardtop with rollbar, and the other is more stock
