Reverting back - "Snow Lion"

Well, I normally consider myself not being a total computer noob, but reverting back from Lion to Snow Leopard somehow went entirely wrong:

I booted Snow Leopard from my clone copy on my external harddrive, started SuperDuper! chose "Mac HD Clone" as source (external clone) and "Macintosh HD" as target (my internal harddrive) and chose "restore". SuperDuper! told me it would do a "copy different" mode. Ok, if working correctly as described, this should do what I wanted: revert the system back to Snow Leopard without changing the non-changed user files to save time. After successful copying and rebooting a somewhat Snow Leopard fired up, BUT: no network card, "Airport card not installed", strange behaviour of the Spinning Wheel of Death and a lot of programs simply hanging when started. I tried to repair permissions on the internal harddrive, but watching the log, where were 1000s of "SUID changed, will not repair"-errors, I decided with my Mac god (thanks, P.) : no way this will be ever running again, because I obviously created a non-working mixture of Snow Leopard and Lion, a Snow Lion...

I ended up wiping my internal hard drive and just "backuping" everything from the external clone copy back to my MacBook's hard drive. Snow Leopard runs like a charm again now. Maybe the SuperDuper! guys might have an improvement on that shortly.

Downside: it costs a lot more time to copy everything than just the changed stuff.
(although my Mac god keeps saying there is no need to do this, this would be improved a lot by using an own volume for the user data and separate them from the system, as normally is done in any Unix derivate, as MacOS is just one of them). Time Machine seems to create a full backup which is again a time issue and in principle not necessary.
Upside: I can really sleep well, since I know now by heart, that my external clone will boot in case of internal hard drive failure and will be copied back within a night of good sleep (and if anything goes wrong there, there is still the Time Machine backup which I didn't need to touch for this at all).