Yes but my point is that it becomes very dependent on how heavy or draggy those wagons are. As a manufacturer you shouldn't have to make a loco so powerful that it has to literally be able to pull a rake of bricks with no wheels on. There also has to be a responsibility for wagon manufacturers to not stress locomotives when hauling them. The longer the real life rakes the more free rolling they need to be really.
As for our haulage tests it will be interesting to see the figures when we do the tests. I did note on Sam's Trains that he used a Newton gauge on the new AS class 60 and reported 1.3 to 1.4N as the loco was bouncing on the spring gauge (average 1.35N?). Not the most accurate gauge in the world but Sam seemed very pleased with that , stating that 1.4N equates to 70odd coaches or something, again not sure where that figure comes from but thats what he stated. We intend to go a bit more scientific on it. We tested our class 60 sample recently and achieved 1.34N on a high quality digital gauge with no bounce. It will be interesting to see the rest.