Looking at the Youtubes, my first impression was that the train must be one of the most overpowered ever dispatched (short of a pair of jet engines on a RDC on the NYC). 6000ish hp worth of Big Boy, 4000ish hp worth of FEF3, and 4400 hp worth of diesel for 9 cars should be more than enough! Nothing needs to work very hard, and all the passbys I saw on Youtube had mainly the BB working, 844 enough steam to keep things loose, and the diesel idling.

The rod packing does seem to be leaking more from the front engine than the rear on the BB, but both are clearly working from the sound. Note also that the weather appears to be chilly (based on clothes people are wearing), which makes steam leaks more visible than in the summer.