I have been using the S2 for over two years and can attest to the S-System lenses being just stunning - better than anything I have ever used which includes, Hasselblad, Fujinon, Rodenstock, Schneider, Pentax 67, Mamiya, Olympus, Canon, Nikon etc etc. The 120 macro is crazy sharp with a superb bokeh - I'd love to put it on some sort of hi-res MDB like an IQ280 to see what it can really do.
One thing to consider regarding cost is that they are virtually future proof - the 37.5MB sensor in the S2 and S does not come close to doing justice to the lenses' resolving abilities. Anything they might bring out with a higher pixel count will work with these lenses, and they are built to last too. I'd wouldn't be surprised if they would resolve fully on a sensor of over 120MP.
I am still waiting to get my hands on the new 24mm, in fact any of the new stuff. It's slow arriving in Australia, the M240 has only just arrived but I expect to get my grubby paws on the new toys in the next few weeks with a bit of luck.