Paul,
Your right they do a shampoo attachment, but it is designed to put a layer of foam on the carpet, and then scoup it up using a single brush roller. It is a tray + solution tank, which fits on the front and makes the m/c very clumsy, and doesnt really agitate the pile. not aware of the carpet massager, know they do a scalp massager, but too small for carpets. I have a Kirby G4. once tried to shampoo my carpets with it (before becoming a CCer) . took days to dry, and looked no different.