Then is it therefore, too untried for the USAF?
How can one come to that conclusion?? The Italians wanted a tanker in service by 2005 when the Airbus hadn’t even flown. Compare that to the KC-X.
Besides, the KC-767NG on offer to the USAF is very different from the adaptations sold to the Japanese and Italians. And the Italian tankers were supposed to have been delivered in 2005.