I think you're up against too many ma and pop power washers. i think when opportunity presents itself .. go for it
However there are many cases for an alternative solution. For example I've got a gas station to agree to apply my NSWR500 stone treatment on their 2 bay garage floors. We are using a heated power washer that produces water to 220 and steam to 330. The heated water at 2800 psi reconditions the surface so quickly and given the use of steam the floors dry quicker than with cold water. You can even use a couple Dri-Eaz units to cut the time so you can apply the surface treatment the same day.
Don't get me wrong I'm an OPer through and through but in this instance I can get the job done quicker with a heater power washer (not mine ... borrowed from my chemical manufacturer).
That said I OP my garage floors and that of my neighbors :-)
