Haven't tried SuperDuper. I previously had used Carbon Copy Cloner, but started having issued with it, and went [back] to Apple's Disk Utility. Its Restore works fine. Been using for quite a while. Reliable, and backup is bootable.
After partitioning your external drive (Mac OS Extended (Journaled)), uncheck "Ignore Ownership...". Then, boot off of your MacBook's OS-X install DVD (or other 3rd volume), and run Disk Utility from there. If the destination partition on the external drive is same or larger, you can do a block copy (re: faster) by checking the "erase destination" box.
To restore, again boot off the DVD, and use the Disk Utility Restore (swapping source and destination, of course).