Thanks everyone for your views. I don't think I'll be upgrading in a hurry, although I might upgrade in the future. According to Mike ORegan, in a previous thread last July, the fixes in 1.5 (and presumably 1.6 as well) are:

1. Bitmap pics for HOME page can now be selected.
2. SD-Card "%age free" is now corrected
3. Drum Track with transposed files corrected for use with MIDI out.
4. Audio files on SD-Card are all now recognised.
5. The SD-Card Control File will no longer be corrupted
6. Corrections to Technichords which either don't work or produce the wrong results e.g. "add9", "madd9"

I've noticed that the SD percentage free is often wrong, but I guess that is a minor niggle. The most worrying defect in 1.3 is the potential for the SD control file to become corrupt, although I have not experienced that so far.

Does any one know what "Audio files on SD-Card are all now recognised" means? I haven't noticed any problems playing audio files.

I wonder if any KN7000s have been shipped from the factory yet with 1.6 installed?