found the issue! Not sure if this is a bug or not, but when I formatted the disk, Apple's disk utility didn't create the APPLE_BOOT partition. I formatted at least 3 or 4 times and it was never created. Then after one more reformat, the magic boot partition was created. Whodathunkit?
Anyhow, a subsequent clone worked absolutely flawlessly, thanks for all your help. Look forward to registering soon.
