My recent experience.I used my recently aquired Host machine on some common area carpets in a warden managed group of flats for the elderly. I also do the weekly cleaning there and know the condition of the carpets.
Also I have HWE cleaned the same carpets in the past to a good result. The main soiling was from general footfall, so very little stain tratment was needed.
The process I followed, (after discussions with a supplier), was vacuuming, prespraying prochem multipro, and Envirodri sponges. These were thoroughly agitated, left in the carpet for at least 15 minutes, then removed using the Host Freestyle vac unit. By volume it seemed that more came out than went in, though there was a fair bit of fluff and loose wool. (don't worry - the brushes were not too hard for the carpet). Further vacuuming was still needed afterwards.
The "dry" cleaning method was no quicker than HWE in terms of time working - where it was an advantage, was not having to refill and empty, (yes itas a porty - not a TM but then again the risk of residents falling over hoses was avoided). Visually the result was as good and the customer is very happy with the result.
Finally there were still some granules in the odd corner the following week :
