The K2600 is the most current synth and its glory days are far from over. It is true that the K2000 is discontinued though.

I apologize for recommending that synth. I didnt see that you mentioned weighted keys. I should have not skimmed through the post so quickly. However, this might be what you are looking for:
http://www.kurzweilmusicsystems.com/html/sp_series.html