I recall that the Santa Fe 2900's were heavier due to World War 2 restrictions on " strategic metals ". Could this mean nickel ??? If so, it could have been a blessing in disguise.
The term " The Greatest Ever " meant different things to different railroads, when referring to steam locomotives. Sure the NYC 6000 class were great performers, on The Water Level Route for which they were designed. On other railroads " The Greatest Ever " could have been a 2900 or GS - Series Northern ( or J or Pocono ), or a Big Boy, AC, Y, or Yellowstone articulated, or a Berkshire, Texas, Mountain or Dixie. The various USRA designs also found favor with many railroads. I recall Trains Magazine having a feature - length article years ago on the subject.