With my experiences of Ccleaner I see that it never repairs the registry it only removes items who doesn't belong there (anymore).
In some way that's also repairing but...
And I've never used the backup although I know it can be riscy but sow-far I never had problems with it.
I think I'm going to start with making a backup because it is indeed a bit stupid if you do not make a backup.
And I also want to say that it is indeed a very good porg.
Jonas