KDE 4.10 has been released, and I have upgraded my old desktop computer that sits on a shelf in our home server room and runs a NoMachine server to have KDE 4.10.0 on it.
First attempt: migrate my existing KDE 4.9.5 desktop environment.
First result: failure. Basically nothing related to kontact/KDEPIM works after this.
Second attempt: delete everything kde related from that home folder (basically ~/.kde*, ~/.local and ~/.config) and try again.
Second result: after going through the “wizard”, kontact/KDEPIM still needs too many additional steps to be actually usable, but after that it sort of works. I have no idea how much of it will still work if ~ is on a nfs drive, though.
Overall opinion: I hope that KDE 4.10 has matured enough once openSUSE 12.3 rolls around with it as the default KDE desktop.