Last year, I bought a base model because I didn't plan on keeping my 1198 for long (just until the new MV comes out), but now I do regret not getting an S just a little bit because:
1) I ended up liking the 1198 much more than I did my Tricolore (S model) and I'm not totally blown away by the new MV; also
2) The 1198 does make a lot of torque (especially if you go with a 14T). I orginally said, "well, my right hand IS the traction control) but in retrospect, I'd like to have it. If I did, I won't be as timid applying throttle over painted surfaces (making right turn and passing through the painted cross walks) because I do on occassion get a little bit of rear wheel slip.
I don't loss sleep over not getting an S, but it would be nice to have. On the other hand, I heard you could add the traction control later on.
I think $20K is a good price for LA since the dealer will be eating our higher tax (almost 10%) and registration fees (whcih went up on 5/2009). I think there's a track day & accessory program going on now too.