Advocate, the answer is no discernable difference. As JT has pointed out, the loadsheet is rubbish in-rubbish out anyway and the margins are a lot wider than estimated CGs to within a decimal point. In any case, the 747-400 has a nose gear pressure switch which senses actual load on the nose & uses this to predict an approximate trim band (744 has 3 trim greenbands - mid/centre/aft). Whatever you enter into the FMC gets compared with this nose gear pressure switch predicted band & if they differ, you will get an FMC message "Check GG". So long as the stab is anywhere in the correct greenband, the airplane will fly. That is a way larger margin than 0.2% MACTOW.