I have the separate sale HHP-8, and one issue I have run across is that it's fairly light and struggles with a larger consist. Since it has a full 8A Cruise Commander and the standard Mabuchi motors, one would assume that it should be able to pull a decent sized passenger train without too much strain. I had nine 18" cars on it, and it manages on the level, but I suspect that any grades will challenge it, I can see it struggles a bit to get rolling. My Genesis with two of the same sized motors and several pounds heavier have no issue at all with the same nine cars. Since it has pretty much the same drive train and electronics (another cruise commander), I feel the HHP-8 could do a lot better. I decided that an extra pound of weight would make a significant difference, and it does.
Given that was the case, I figured I'd take a "shot" at solving the problem, note the weights.