Unable to find any easy resolution to the DVD install hanging, I downloaded the GNOME live CD version, this ran just fine and the installer also worked. Of course, being in a VM, no acceleration was available, so I got the fallback GNOME look. It is interesting (to me anyway) that opeSUSE's fallback GNOME look is like the default look of old and not like openSUSE's customised GNOME.
Extra repos and such like seem to work fine. If anything the package management (for which there is an update) seems to work faster than in the 11.4, though whether this is due to having a GTK front-end rather than the dodgy KPackagekit effort, I don't know.