For what it's worth, these RK NW2 are fine running engines, at least mine was. It ran great on PS2 and runs just as smooth on BPRC. The ONLY problems I had with mine were early on. (1) found 1 single strand of wire on one of the trucks causing a short, easy fix and (2) when my layout was in the garage it wouldn't run in temps below 50 degrees. If I turned the heater on before I ran trains or if it was above 50 degrees it ran great. Since I've relocated to inside the house I never had another issue.
It was tight getting a 9.6v NiMh battery inside along with the receiver board, on/off switch, and charging jack, but I managed (glad it was a bit bigger than scale!).
So I measured the truck centers on mine. The truck centers are 24'-6" on the model, 22'-0" on the prototype (according to the book I have, Seaboard Motive Power, by Warren Calloway and Paul Withers), think that comes to 5/8" too long between trucks. Not sure where the rest of the discrepancies are.
Another photo:
This time the rollers are gone and it's sitting on Micro-Engineering code 148 2-rail track. All my stuff still has 3-rail wheels but my layout is all code 148 2-rail. So far everything runs fine, except I think the flanges hit some of the spikes on my hand built switches, no problems with #6 switches from Signature Switch.