Well, I've completely given up on the commercial Digium Fax for Asterisk module. After completely rebuilding my config to test the module I encountered tons of issues. Faxes were failing 99% of the time. I rebuilt the free app_fax with spandsp and straight away things were back to 100% success rates for both sending and receiving.
Sorry Digium but you just can't compete on this front.
The tech support offered to me after my last post was polite, but you can tell that they are not intimately familiar with every portion of Asterisk and seem to overlook details from previous communications. It was a nice notion by Digium but notions don't make products work!