I was afraid of updating too, until I hooked up the Audya to my PC and started looking at what is involved in updating, whis is the .mem portion. It looks to me that if your machine is working properly, there should be no problem. If there is, delete it and run it through again.
I, like Don, don't see what the changes are, but I look at it like insurance. There must be a reason to issue it, and if and when I try and do something, there will be a better chance of it working correctly.
From the Ketron site (what the update do or fix):
NEW UPDATE 4.2B
1.Remarkable Improvement on Midi Clock send external Sync.
2.The present Play List is now annulled as soon a .mid, .wav or .mp3 is saved.
3.Whenever a Single or Block Registration is loaded, a Program Change is sent.
4.From this version on it will be no longer necessary to manually deactivate the Mp3 Transposer to avoid that while changing the Tempo of the Style being executed the pitch is modified. From now on the instrument does everything automatically.
5.During the Swell to Right the General Volume value that was active when this function was selected, remains in the memory.
6.The Footswitch was enriched with the following controls: Back/Forward Tab, Enter, File Up/Down, Sub Reg. Up/Down as well as all Tabs from F1 to F10.
7.New Reverb, Phaser and Flanger effects.
8.The Global Search now works correctly in the Registration area.
9.The User Audio Drums in the Registration can now be handled correctly.
10. For Vocalizer to Arranger the OFF value can be set.
11. The Expression Pedal curve was optimized.
12. In the Pattern Edit Menu the Quantize as well as the Pitch and
Modulation controls were improved.
13. The following functions were optimized: Registration, 2nd Voice, Separate
Outputs, Karaoke, Ins, Msp, Footswitch and many more.
14. The Audya 4 can be reset by pressing the Exit+User5/10 keys at the same
time.