After years of wondering how effective they are I have had a demo of a host freestyle machine. All I can say is I'm not impressed. It left quite a lot of sponges deep down in the carpet. The sponges also seem to get lodged somewhere so when you are vacuuming if you hit the machine against a item slightly some sponges are left in a small pile which then need to be vaccumed again. It was however an effective pile lifter but at the price an envirodri would be a lot more attractive.
I have to say after using it in a couple of settings my sebo duo with duo P and an upright vac has been easier and more effective, for the jobs where dry has been necessary.