Hey Adrian,
Well, basically, the backup strategy isn't successful unless you can successfully restore the database to the RSG and then mount it. I imagine that you could restore a corrupted database to the RSG, but then you'd need to mount it and use exchange recovery tools to fix the database.
I would say in general though, that if you're able to restore a database to an Exchange RSG, that it's pretty likely that your database is in good shape and you can consider the restore process a successful one that should also work in a live environment. Just make sure that you're familiar with the rest of the process required to recover all of your mailboxes and settings.
- Scott