"What is the "truth" and "half-truth" concerning the number of people who have died flying an A-400M vs a KC-46?"
Being as the KC-46 is a development of an existing design...Over 700 people have died during the 'development' of the KC-46.
The problem with comparing apples (KC-46) with oranges (A400M) is that the stats can be manipulated as required to suit an agenda.