Thanks for the KBA link and clarification. It seems I've learned something new about the way PGP WDE works. For my purposes, an uncrypted backup image is fine. I was more concerned with the possibility of an outside attack not being required to enter the WDE passphrase, using the above process to create a whole disk image, restoring the disk image to a newly formatted disk, and thereby bypassing PGP WDE altogether. Of course, based on what you're telling me, this doesn't seem possible. I'll test it for my own peace of mind as soon as I get the time.
Interestingly, this also seems to explain why I was unable to boot from the backup image when I initially restored it. I was in fact using Acronis in "Whole Disk" imaging mode, but I was not performning a sector-by-sector backup. So, I may have had an encrypted MBR, but unencrypted OS partition. Or, I may have simply had the PGP bootloader installed to the MBR partition but the complete disk image (MBR, System Reserved, and OS partitions) was unencrypted. I may or may not revise my backup procedure based on this information (in an effort to make the restored image bootable by default & save overall restoration time). Thanks again.