Wheres 411A when we need him? LOL.
On the Tri-star, with the -200's,250's and -500's, the 524's would out climb the wing. The 747 is the same way. The wing can only do so much work at a given weight and altitude. The engines are way more fuel efficient, but the wing is the limiting factor at that point.
Thats my wine influenced point of view.