from what I have heard about it it is like the magnum top gun modulator. you can turn it on and off. depending on the version you get. all it basically is a diode and resister put in R238 or R264 depending on what board your radio has. works in the 3600 or 6900 boards.
if you look at it on the auction sites it is a unit made to look like a disk capacitor or some have it looking like a electrolytic capacitor. works on the AM side of the radio only. I have cut them open when they quit on people and all that is inside it is a diode and resister. some have 2 wires that do not go to any thing inside the module and they have you hook the 2 wires up to ground and 12 volts. the 2 extra wires as I stated do not do any thing. the only units I have seen that actually do hook up to ground and voltage is the top gun modulator which works on AM only and magnum has the top gun compressor that works on SSB side of the radio. so do not waste you hard earned money on the Dominator as it is just putting 10 cents worth of parts in it to give you swing. you can get the same thing by lifting one leg of R238 or R264 depending on the board you have in your radio and add a diode to it.
your main question was does it work, so yes it does work and is in about 90 percent of the truck drivers radio out there but it is the diode mod a tech puts in to increase modulation. the info is all over the web on how to do the mod.