For Garage Cleaning, we use 0 degree nozzles. They spin in the opposite direction that the wand wants to go due to the Gas Motor on the Surface Cleaner. We did a test between that motorized and the big guy surface cleaners. BOTH are good, however we found that the motorized surface cleaner cleaned a bit deeper and faster. The big guy has it place though, It is easier to handle, weighs in about 1/5 the weight, and no time for set up ( Gas, OIL, Multiple Grease points). For small and /or tight jobs, Big Guy is The Clear Winner!
For garage cleaning, we use 0 degrees. For walkways its 15 or 25 degrees.
In a GARAGE setting, we clean 65,000 to 70,000 sq ft in 4 to 5 hours with 1 motorized surface cleaner, not including rinsing or prep work. Big Guy we cleaned 65,000 in 6 to 7 hours (About 2 or so hours longer) Reason, we had to walk slower with the 0 degree's installed on the Big Guy because the wand underneath could not spin as fast (up to 2000 RPM's) as the 3600 RPM motorized surface cleaner. We tried with 2 nozzle and 3 nozzle setup. It appeared that the three nozzle setup worked better than the two nozzle. Other than the speed of the wands, they both had the same spec's.
We also noticed that the surface cleaners that had to be propelled by the water force, had less pressure at the surface cleaner than that of the motorized units. The self propelled wands took approximately 400 to 500 psi to turn at the end of a 1/2" 200ft hose. The motorized one actually did a little better at a loss of 150-200 psi.
