Maybe I'm old, but four engines with a PFE onboard is my preference. Nice to have the A&P qualified PFE when you need him for a mechanical at some third world, watering hole charter destination.
Obviously a man with very good sense above!
As for FedEx wanting more 777's, remember that Fedex and UPS both carry small packages for the bulk of their load. Therefor, they cube out the aircraft way before they have to worry about weight.
As for the numbers on the -8, I was in a meeting three weeks ago with the V/P of flight operations. The number that was given is 437 gallons less per hour than the 777 so I think they must know if they are being that specific. Seeing that we have over 20 -8's either on order or optioned, I think that Boeing is giving us real numbers.