if you're looking for a moutain/fun/dd car, buy the g35 or 350z and do some suspension mods. that will probably be your best bet..... I dd my S, but i am not one that craves creature comforts.
oh yea, most s2000 mods are done for weight saving purposes. an aftermarket exhaust may only gain miniscule horsepower, but a good single can lose you around 40 lbs without going titanium which could lose you about 50 or so lbs.
and the convertible sucks in winter because of the heatloss from a canvas top instead of a conventional metal top with headliner.