Critique My Backup Strategy

[New Guy]

I'm trying to get serious about backing up my family's iMac and the strategy I'm working with now is this:

The 750 GB internal HD is cloned every week, using SuperDuper, to a 750 GB external HD attached via FireWire to the iMac.

I have (on order) a 2 TB external HD attached via USB to my AEBS (located in my basement and attached to the iMac via ethernet) that I will use as a Time Machine backup for my iTunes library (I have iTunes Match so this may be unnecessary) my iPhoto library, my home movies and my documents.

This way I have coverage from accidentally deleting a file (Time Machine) and coverage if my internal HD fails and I need to get back up and running quickly (Cloned HD).

I'd—eventually—like to have a second cloned 750 GB drive so that I can alternate and keep one offsite (will SuperDuper alternate between the two?).

Am I missing anything?

I'm running Mountain Lion if that makes any difference.