Chem Dry!
http://www.chemdry.com/
Have used numerous places before , and they always took 2 days to dry and used those loud
noisy machines mounted in the back of their vans. Not chem dry, and they are a green company, meaning
they dont use nasty chemicals. I wont use another company again they did a great job!
The companies that use hot water extraction use a very mild detergent and rely on the water to do the heavy lifting. Chem Dry also uses a mild detergent ("Based on Natural ingredients" as is pretty much any soap ever made). The "carbonation" is a gimmick.
The the chem dry pads will still leave detergent residue in your carpet, it doesn't magically disappear from being wiped with a pad as you need water to dilute/remove it; so it's not better in that regard than a water extraction cleaner which can flush the detergent away.
In my opinion the benefit of Chem-Dry system is that it uses less water, so it can dry faster. And if you live in a humid household you don't want to leave carpet pads wet.
And in my opinion the biggest drawback of chem-dry system is the heavy, powerful, floor scrubber. If it snags a carpet nail at the edge of the room or a transition between rooms or flooring types you might lose a large section of carpet or even risk damage to furniture and walls.