Or, to put it another way, D-IFF_ident:
To match the offload of the KC-45A using our test scenario, you would need 1.65 KC-767s. If a KC-767A has a burn rate of 76% of that of the KC-45A (which frankly I doubt), you would thus burn 1.65 x .76 = 1.254 the fuel the KC-45A would burn.
25.4% more fuel burn, twice the crew, twice the maintenance costs - does that really make sense?
The intelligent customer chooses Airbus!