I don't remember just what the figures were, but a few years ago we made a policy that all a/c should be loaded in the aft 20% of the trim range. I seem to remember savings of about 3% or so. Very signifigant if your fuel bill is many millions each year.
Makes little difference on short hauls, and I don't think the a/c type would have a major bearing. All a/c fly by the rules of aerodynamics.