In Distrowatch Weekly, they refer to long-time Mandriva user, who now switches to Kubuntu.
The note is here.
The long Goodbye note from Erwin Van de Velde is an interesting article –
I'm leaving you for a new adventure in (K)Ubuntu-country. However, I'd like to
state here the reason for this decision:
With Mandriva, I had the choice: staying up to date in an unstable release or
staying way behind with stuff like KDE in a stable release. This is not the
kind of choice I want to make.
The club membership I had for one year at university was a big disappointment:
ATI drivers were not up to date with the latest kernel, KDE 3.4 could be
downloaded but there were even no security updates, getting the Mandriva 2006
DVD two weeks before the community was impossible (missing ISO files, corrupt
ISO files, … in short it took two weeks to get the DVD).