Being in a rather venturous mood, I decided to try out the upgrade-from-DVD feature on Xanthippe (I don't really want to hunt down every package of additional software again).
For starters, I dumped gzipped partition images of my system and home partitions (cf. daWuzz) on an external disk. I used knoppix to do this (and to format my external partitions), I am not sure whether one can dump the system partition of a running system. Caveats: to write to a drive in Knoppix, you have to enable write support (right click to drive's desktop icon). For the dumping you have to be root - there is no root password set by default, so sudo su won't ask for it.
During the update process (update option is given after the system analysis) the installer analyses the software repositories present on your system. Provided you get the internet connection working in the next step (which I didn't :-( ), you might manually change them to the corresponding SuSE 11 repos. Lacking a LAN connection, I had no 11.0 Packman repo available and got a small number of conflicts in the software selection, which could be resolved by downgrading to the SuSE versions (stuff like Amarok, Ktorrent or wxGTK).
The following update took approx. 2 hours (might be just due to all that additional packages), which is of course quite a bit longer that a clean install (1/2 h?). So if you don't have a lot of additional software and settings, you might consider to just leave your home partition as it is, do a clean install on the system partition and install by hand what's missing.
OK, bad news: during boot, the system gets stuck on endless repetitions of
hub 2-3:1.0: unable to enumerate USB device on port n. This is the 2.6.25 kernel's reaction to my faulty internal USB hub - still, I can't get the updated system to boot that way.
I will try a clean install next...
Clean install notes:
Automatic partitioning setup even includes mounting my former home partition, which is quite nice. Not quite so smart: the user setup still just offers to create a new user, the "import old users option" is concealed behind the Change... button.