Well, I got home this evening armed with the V4 disks, expecting maybe a few undefined 'operating system grades' and no real fixes. This is usually what has happened in the past going back to KN5000 days, but boy, was I in for a big surprise!
BOTH my major gripes have been fixed. Chord recognition speed is now spot on, I can't fail it at all even using all the standard tests I'd found that made V3 and before fall over. Songs that sounded awful when played with the older software versions are now perfect. The other fix is to Technichord notes resounding when the left hand chord was released and then the same one pressed again, although this may have been a consequence of the chord recognition.
I'm so glad I held out for a fix, rather than trade it in for a PSR9000. Anybody out there who has been wavering about buying one because of the well publicised problems, worry no more!!
Thanks Technics, my faith is restored!