I have the Progressive EMS-HW30C and have been happy with it. I do not have a transfer switch, just a generator out receptacle that you plug the shore cord into. I wired the shore cord into the EMS so it protects from either shore power or the generator. It works fine and I have not had any issues with it. I like the remote indicator, as I am always looking at voltage as A/C, microwave, and water heater are used (microwave and water heater share a circuit with a priority box that allows the microwave to run and shuts off the water heater. When microwave stops, water heater gets it power back.)
I am a technical person, so being able to see the volts, amps and cycles is nice. The long delay is 136 seconds. Some new A/C units have time delays built into them, and if yours does, you can go with the short delay.
Charles
'03 Ram 2500 CTD, 5.9HO six speed, PacBrake Exh Brake, std cab, long bed, Leer top and 2008 Bigfoot 25B21RB.. previously (both gone) 2008 Thor/Dutchman Freedom Spirit 180 & 2007 Winnebago View 23H Motorhome.