I've got both a
Subrau Gas Presure washer (3100psi 2.4gpm)
And an electic
Pressure-Pro washer (3000psi, 3gm)
Hands down the Pressure-Pro is my go to machine if I have 220v avaiable. In my experience almost all gas powered washers will wake the dead (or the nieghbors) at 8am on a Sunday morning. As far as the foam cannon goes the MTM Professional Foam Cannon with a 2.5 - 3.0 gpm pressure washer gives far better results than lower rated consumer washers and cannons. So, what is the down side to a professional electric washer? Well, the Pressure-Pro is 10X the price of the Subrau.
But, the pump is rebuildable using an inexpensive rebuild kit, so the whole system will last a very long time compared to consumer grade washers.