I have a 2000 w/ 65K miles and love it too!!! Just had my first "known issue" with the water reservoir developing a leak and needing to be replaced. Check the cap on the reservoir and see if it ends in 00 or 01. If it ends in 00, replace the cap ($20 at the dealer) with the revised 01 cap. I think it helps with pressure relief to try and keep your tank from cracking.
I don't have any RMS issues. I have one pulley and one of the radiator fans making some noise so I'm replacing the bearings soon.
Other than those it's been maintenance only.
For "S" or not, if you have driven anything with more HP, you may want to go with an "S". The Boxster was my favorite car to drive until I got the 928. It feels so good to be shoved back in the seat w/ 320HP that I don't miss driving the Boxster as much. That's good for me since it's my wife's DD, but if it had more power it would be my favorite automobile by far.