The difference is not huge. KC-46 MTOW: 415K vs. 126lbf is about .3 & the KC-135R MTOW 322K vs. 84lbf is about .26. I'm the difference becomes more beneficial in hot places.
Also I thought I heard from someone that they will not really ever be able to use all of those 18 pallet positions for some floor loading reason?
Does anyone know if they are updating those gameboy cameras they installed so the boom can actually see worth a shit?