When you use the Automated System Recovery applet to restore to a replacement disk of identical size, you receive:
Setup was unable to restore the configuration of your system because of the following error:
The capacity of the current system disk drive is insufficient, and cannot be used to recover the partitions on the original system disk.
The replacement hard disk drives must be at least as large as the disks present on the original system.
This problem will occur if the replacement disk is slightly smaller that the original disk, even though it appears to be the same size.
This behavior may be due to differences in disk geometry, rounding errors in the display of disk space, or differences in the firmware on the same make and model replacement.
The only resolution is to use a disk that has the same disk geometry / firmware as the original disk, or to use a larger disk.