Just looking at it, and i am partial to this view all because its not what its made of but who makes it.
Every piece of equipment uses the same brands of pumps, motors, belts, boilers, burners, fuel pumps, rails, fuel tanks, frames, and so on. Its all about who puts it together. The quality that we look for as a company is something we can send out tech's with and not have them coming back to the shop holding the burner cover in their hands and the gas can in the other. I want machines i can service regularly, replace whats needed, and not have to worry about the thing falling apart but also not spend 10,000 on each skid.
Pressure pro buys their boilers and frames from Alkota then assembles them cheaply ( skid models I know not sure about hot boxes) which is the case with this company i am sure as well but maybe not Alkota.They all use either a brigs, kohler, or honda engine mostly, all use a general pump, cat, or in the case of landa a proprietary pump made for them. The real difference is in the small stuff like how they attach the controls to the frame, or the bolts used to secure the burner to the frame, engine to the frame, lineing up the pump and shaft, or the hose they use for bypass and connections on the skid.
I have alot of problems with alot of manufactures but there is a reason we get what we pay for just as our customers do. Are we hacks becasue we purchase a poorly built Pressure Pro machine vs. Custom build (ala Jim) or Landa (good products built well, but $$$$) or are we the same as our customers wanting to find that perfect match of quality and price