I've flown the 757 to La Paz. I also flew as a passenger on a 727 out of La Paz. The 727 takeoff roll took 33% more time than the 757's.
A 727 has a thrust to weight ratio of approx. ..24-25:1. The 757 has a thrust to weight ratio of approx. .34:1. That's an increase of 36-41% in the thrust to weight ratio.
Have you actually commanded a 757? At high altitude airports? 36-41% more thrust to weight is significant and a huge improvement in performance, especially at high altitudes.