Okay so about Time Machine...it's not so much a backup solution as it is a combined backup/transaction logging/versioning system. You don't get multiple copies of your files backed up. You have a single backup and then a record of all changes made to the file(s). Think of the way non-destructive photo editing in Aperature works...you have a database that records each and every change you make to your photos so you can always roll back to a certain point. You will also be able to determine exactly what you want covered by time machine and for how long. Just clearing that up....carry on.
.Mac Needs to Be Radically Retooled