Squeek,
The aftertouch sensitivity was addressed several OS's back. I play the 9000 on the job every night, and have never experienced any of the other problems, even with the prior OS's.
The latest update repaired a couple of minor things such as the placement of an up and down arrow on the Data Base page. The other things each OS updated can be found on the Yamaha PK Club page. One previous update repaired a minor problem with the Registration Memories making errors with DSP on some voices. I also heard that part of the polyphony problem (that I never experienced either) was caused by some errant midi messages and that was repaired.
The bugs on the 9000 were very few in comparison to those of other keyboards, and to Yamaha's credit, they react quickly to repair them when they become apparent.
They did probably release the 9000 a little prematurely because it didn't even have Style Creator fully activated on the first OS.
Oddly enough, the gooseneck lights are one of the features I look forward to. I now carry around two clip-on lights to all my gigs. Yes, I can navigate it in the dark, but I would rather see it, just in case.
The one feature they still need to address is making the thing load medleys of midis. Even the "lowly" PSR740 does this. (Are you reading this Yamaha?)
My opinion is, I wouldn't worry about any remaining bugs.
Please email me or visit my web page and leave a message if you have any specific
questions. I'll try to help.
DonM