I find the PRO900 allready a LOT more organic sounding than the PRO750/2500. Especially the highs are much better.
I also like thew PRO900 better than the ED9. The ED9 are veiled in my experience... Besides, the PRO900 are a lot more comfortable than the ED9.
My PRO900 have only had about 50 hours of use yet, so they may change some in the near future (I hope the bass tightens up a bit).
Another remark: these phones are incredibly good for PIANO. (the pro750 where allready very good for that, but the 900 are even better).
How do the new PRO900's compare to your Kenwoods (before & after mods on both cans)?