Below are distribution notes from past experiences. If you have additional notes that you would like to add for other distributions, please forward them to me.
The largest change for Debian based systems is the lack of anything analogous to RPM's integrity checking capability, rpm -Va, which we use to check for correct restoration. debsums is close but has other problems. You must install debsums, as soon after installation as possible. You must then run apt-get clean && debsums_init. This command will force the reinstallation of packages for which checksums have not already been generated. Package reinstallation can affect configuration files. Also see the caveats section of the debsums man page.
The most practical problem is that Debian and Ubuntu use UUIDs to identify partitions, rather than device files or labels (like Red Hat systems). We can preserve the UUIDs, and assign them to ext2/3/4 and swap partitions. Actually, we can get UUIDs for any partition blkid supports.
The scripts now reflect Fedora 7, so you should not have to make any changes to these scripts.
I tested the above on a fresh installation of FC3. I had problems with devices after booting when I worked with a system that had been upgraded from FC2 to FC3.
For me the best thing about using Knoppix is that I don't need a specific boot medium for each machine, but I can use the same tools all the time. And hardware support in Knoppix is really great. I don't have that much experience with different platforms, but all the machines I've tried have worked fine, scsi drivers are found and so on.
I'm doing this recovery thing by copying the backups over the network to other machine. The restore involves booting the Knoppix cd, fetching the metadata.tar.gz from the network machine. Then make.dev, mount.dev, fetching the other tar.gz files, grub and reboot. Some typing involved but thanks to your scripts it's quite straighforward. Unless changing from ide to scsi or something, but even then it's not that difficult, since Linux is easy to restore to different hardware.
Let me add to that that Knoppix detects USB devices for you, which is really nice. They make excellent (and roomier) substitutes for the ZIP drive.
Also see "System recovery with Knoppix".
Do your restore as user "root" rather than as user "knoppix". Otherwise you may get some directories and files owned by an oddball user or group. Also, for Knoppix, we tar the first stage stuff saving numeric user & group values instead of by name. The names may point to different numbers on Knoppix, so we would be restoring the files with incorrect user and group IDs.
Finnix has some of the same advantages of Knoppix. In addition, it runs in command line mode with mouse support, which is great for the task at hand. It's small, under 100 MB as of this writing, so you can remaster it with your first stage data on it. It boots quickly. And it has LVM support. And Zile, a subset of Emacs. It is small enough that you can load it into RAM (finnix toram at boot) and use the CD-ROM drive. I am pleased with Finnix for this use, and it is now my standard first stage restoration Linux.