You didn't mention the can fan max line. It comes with a three speed controller attached. I'm using a 6" max fan in a 4x2x7 ft. tent with about 1000 watts LED and it's doing a great stealth job, as well as maintaining the tent temperature at abut 80 degrees, or about 7 degrees above ambient. It's running at low speed, about 280 cfm, before accounting for flow loss through a 550 cfm rated Phresh filter. The tent is in a closet separated from the living room/reception area by a thin cheap door. The exhaust exits through a 13" phat muffler. You cannot near the fan unless you put your ear right up against the closet door. Then you hear a background hum that sounds like there nay be a refrigerator in the closet. I've had scores of all kinds of people walking through the area and sitting in the living room and no one has noticed or commented on noise.
You may want to give the can max fan a look.
Good luck.