Kevin,
Indeed, as you say, ther was never a need to doublehead down grade anywhere on the NG. Just to clarify my comment, it was simply a matter of convienence not to take the time to cut off helpers down the grade from Falfa to Durango and in other similar places. I would tend to doubt the rate of pay for the specific miles run light would change as long as the engine crew did indeed perform helper service on a given timeslip. However, my cynical nature derived from working for a major carrier makes me sure someone in Denver's timekeeping dept. would have done there best to try it!