Ah, I just saw this:
http://www.shirt-pocket.com/forums/showthread.php?t=87
It would be helpful to have this information somewhere in the interface or in the documentation. You might also consider doing some usability testing of the interface if you haven't already (it seems largely intuitive but the fact that I've cloned a drive three times in a row do to not understanding the SuperDuper! scripts after reading the documentation stands for something...). -Joe