I've swapped email with Electrosport again....
Their design includes a better grade of wire (for lower resistance and thus lower internal heating), as well as a different winding design and a few other enhancements. I'm hopefull that their design could resolve our problem. They will begin testing soon.
Just to re-iterate: I strongly recommend all owners to install one of the many available devices that monitor system voltage so as to have advance warning of charging system failure.