SuperDuper gets a lot of guerilla marketing, almost unfairly.
It's ok, it does "call home" when you launch it (install Little Snitch), which I find a substancial security risk for a program that takes your admin password. (after all programs can alter other programs)
If have found
Deja Vu more to my liking, it's a System Preference pane that auto clones and auto backups when you want, even when your logged out, even over a network. Guess it almost qualifies as spyware 🙂
http://www.apple.com/downloads/macosx/systemdiskutilities/dejavu.html
I have written detailed instructions how to clone reliabiliy on my site
http://homepage.mac.com/hogfish/Personal6.html