No, I didn't test the backup. Lesson learned! Hard to say what caused the initial failure as nothing odd occurred during the backup update.
Other lessons: In this instance Migration asst. is a waste of time.
Last night, I booted again from my MBP external cloned HD. Then, I ran SD, copying the desktop's clone to the Desktop HD. I knew it wouldn't boot, however, just wanted to return the existing info to its cloned state. When done, I ran the Leopard Installer>Archive & Install. All is fine now except for some minor application issues.
Again, lesson learned. Thanks Dave.