Migrating between Distros

[Jonathan Hutchins]

With the prospect of the death-of-product for Redhat 7-9 looming, we've 
discussed possible alternative distributions.  One thing we haven't discussed 
is migrating from one distribution to another.

Obviously, the easy answer is to build a new system, install the new 
distribution, tweak it up until it does most or all of what the old one does, 
then pull the plug on the old system.

With a desktop system, you could do this in multiple partitions, although 
having to reboot to check the settings in the old one would be a pain.

The real test, though, would be to "Upgrade" the existing installation, right 
there on the same partition, hoping to preserve at least some of the 
configuration, personalization, and package choices.

Most distros have an "upgrade" function that is supposed to allow you to step 
from one release to the next with relative grace and ease.  I know that going 
from Mandrake 9.1 to 9.2 wasn't as smooth as it should have been - lots of 
KDE stuff had to be re-installed for instance.

I really don't think that I've seen anything where say a SuSE installer would 
offer to preserve the setting in a Mandrake installation while "upgrading" to 
SuSE.  That's probably because I haven't really looked - haven't booted a 
SuSE install disk on the Mandrake system.

Has anyone done this?  Migrated a system from one Distro to another without 
just doing a clean rebuild?  What advice, warnings, or suggestiosn do you 
have for us?