My system works great.
I have a working disk. 2x 100GB OWC SSD's in Raid0
I have a droplet in my finder which works with a program called Hazel.
Once a project is finished I drop the file onto the droplet and it saves it to 3 places.
First is Main storage drive on the Mac Pro. It's 4x 3tb Hitachi Deskstar drives in Raid0 to make one 12tb Drive.
Second is a bare sata drive in an esata caddy/dock.
Third is a bare sata drive in a second esata caddy/dock.
So I have 3 copies. One local for me to access, one filed away (when the drive is full I print out the finder and put both in an envelope) on site and another which I send offsite.
I also have a G-Tech G-Drive working with Time Machine to cover the working drive.
On a side note, Hazel is also great as it allows me to automatically import retouched finals into a lightroom catalogue for reference as part of the final saving and backup process listed above.
Bare sata drives are cheap these days (maybe not so much at the moment after the Thai floods) Just go to google shopping and select sort by cheapest price.
Here is the dock I bought:
http://www.storagedepot.co.uk/External-Hard-Drives/Hard-Drive-Docks/sc883/p753.aspx