Is 'disk Image' really necessary?

[MMM]

Two quick questions:

1.) We noticed a feature called "After copy, create a disk image of backup". Ordinarily we just do a smart backup to another partition. Should we also be making a disk image, or is the smart backup all we need and a disk image would be redundant?

2.) Also, we have two partitions, the main OS X partition (which is what we normally use everyday) and our 'Backup' partition (this is where SuperDuper stores its backup at). Let's say that one day our Mac crashes and we can't use the normal OS X partition anymore. How would we copy our 'back up' partition over to our OS X partition? My guess is to format the OS X partition and then copy all of the back up files into the OS X partition, but not having ever restored a backup we're not sure if that's correct

Thanks