lets think about it. 767 was the first twin jet to do the atlantic. it has a long good history.
I can't think of any thunderstorm related crashes for this type. I do remember the inadvertent thrust reverser deployment tragedy.
While the Airbus might be a bit more efficent...its all about combat capability and reliability.
So, how come France, Germany, Spain, and England don't buy the airbus as a tanker?