Obviously, I'm a bit biased in that I own and love my S2K (my second one, BTW). I was curious in reading this thread to see what you guys thought as I came very close to buying a 1994 NSX instead of my second S2K.
In the end, I chose the S2K becuase I was going to finance 50% of the car and as much faith as I have in Honda, I couldn't get comfortable financing that much $ (roughly $16K) on a 8 year old car. I don't use the car as a daily driver but I do put on about 12K miles a year and the NSX was just too big a bite for me.
That being said, I've always loved the NSX and someday hope to own one. I've toured the factory in Tochigi prefecture where the car is built and still consider the NSX to be one of the most complete, most beautiful and most balanced designs ever.
Having spent quite a bit of time (for a non-owner) behind the wheel of 91-94 NSX's, I'd like to throw my 25 cents into the mix.
First off, the NSX is the superior automobile. There's no two ways around that. It should be as you can almost buy three S2K's for the price of one new NSX. It's more powerful, more comfortable, more refined, and faster in almost any condition, any weather than the S2K is.
However, there are a couple of areas that the S excels in. The shifter is the first. The NSX shifter is amazing, to be sure, but the throws and feel of the 6 speed in the S2K is better, IMO. Also, the brakes. The S has better brakes (both in terms of feel and pure stopping power) than the older NSX's that I drove. Finally, the headlights. I'm sure the newer (less elegant, IMO) headlights are better but the older pop up headlights were nowhere near as good as the HID's on the S.
Having said that, the NSX has a much more powerful motor. Both in terms of low speed tractability and top end power. While, I honestly don't think the S is all that bad in low RPM, around town driving (it isn't a dragster after all and keeps up or ahead of almost all traffic without getting into VTEC) you can't compare the grunt of a 2.0L 4 with a 3.0L or 3.2L V6. I do find it interesting that some bash the NSX for not having enough grunt and now they say the same about the S. The NSX is also way, way, way more refined. The cockpit of the NSX, IMO is second to none. It's both an exciting and comfortable place to do "one's work". The sightlines are great (so are the ones in the S as long as the top is down) and the materials are very good. I, for one, like the stark uncomplicated interior on the S, but let's call a spade a spade. It's obvious that Honda didn't spend the $ on the creature comforts on the S.
The NSX is a much better GT car whereas the S is much better in autoX. I'm sure much of it has to do with pure size and wheelbase but again, you're talking about two very different cars.
In the end, they're both amazing cars, IMO. I'm still amazed at how much car you get for $32K when it comes to the S as am I amazed at how far ahead of it's time the original NSX was. Back in the day (when it was $60K new) the NSX was leap years ahead of the Ferrari 308, decades ahead of the 328, years ahead of the 348 and as good if not slightly better than the 355. It seems that the 360 might have eclipsed the NSX but hey, that's 10+ years later and it's a whole lot more coin. Moreover, it still doesn't even begin to compare to the NSX with respect to livability, maintenance, and durability.
Sorry for the long winded approach but I wanted to throw my hat in the ring. You guys enjoy your NSX's. I'll enjoy my Spa Yellow 2002 S2000 and be green with envy until I can afford to run with you guys.