A good example of less water volume but decent pressure is of those "home owner" type pressure washers that run on a 120 volt 15 amp outlet with something like 1.2 gal as they seem useless to drill through anything such as mud compared to a real pressure washer even more on the lower end of the scale at 1500 psi and 3+ gallons output for an example. The more water volume one can have seems to bring the pressure washer action alive just like a relatively low pressure fire hose because of the sheer volume of water.
What surprises me is that you haven't had paint flying in all directions when you were using your 3500 psi washer and I wonder if the nozzle fan angle was wider so as not being as aggressive as it would have been with a narrower angle. Also did your wand have the slight bend at the end where the nozzle screws on as the longer the wand is, the worse it becomes to fight against that thrust and expect that is part of the reason they go with straight wand ends at truck washes.
If you could get a fair demo of a side by side comparison of models, actual washing conditions on a Super B, then it would probably answer the question pretty quickly.
What surprises me is that you haven't had paint flying in all directions when you were using your 3500 psi washer and I wonder if the nozzle fan angle was wider so as not being as aggressive as it would have been with a narrower angle. Also did your wand have the slight bend at the end where the nozzle screws on as the longer the wand is, the worse it becomes to fight against that thrust and expect that is part of the reason they go with straight wand ends at truck washes.
If you could get a fair demo of a side by side comparison of models, actual washing conditions on a Super B, then it would probably answer the question pretty quickly.
