Assuming that trailer brakes are designed to stop the trailer and not add braking requirement to the tow vehicle, then shouldn't the rankings of towing vs. not-towing stay the same?
I ask this question, but must say that I am NOT impressed with how the F150 brake controller electronically regulates my trailer brakes. Yes, it is smooth and unnoticeable, but I wish it let the trailer do a higher amount of the work. If I pinch the manual brake lever to 100%, it would take my trailer nearly a mile to stop us from 45mph. I know the trailer brakes are more capable than that. They were on my last combo that used a different controller.
I'm dealing with a pulse in my truck brakes due to warped rotors. I think they are warped from the above concern.