We install soft starts on all our pumps over 25 HP. They are solid state controllers that reduce voltage to the motor during start, then a very heavy set of tiny contactors close under no load, and the electronics then go off line. What I think is unique about the Dometic device is that it supplies full power to the air conditioner all the time, and probably drops the voltage for a short time when it senses the high starting inrush. A pretty clever idea.
Gary H. Lucas