Apparently Kubuntu 13.10's version of the fglrx driver is now equivalent to the beta one I added to my 13.04 install to get it running, so I decided to do the upgrade. However, it kept failing with a cryptic error that it couldn't do the upgrade because I was either running a pre-release ubuntu (no) or upgrading to a pre-release (no) or using some unsupported package (well, sure, but which one).

Turns out this warning was generated by having "held" the xserver-xorg-video-intel package in order to get the fglrx beta to run. apt-mark unhold the package and the upgrade is now running.