Hi Guys
I cleaned over half a million square metres at M&S head office (not in one day

) using rotary with shampoo and brush.
In those days , 70's, the process was called crystalisation , which is basically the same as encapsulation although the chems are probably better now.
Results were O.K , carpet was cleaned approx once per year.
As for brushes they were worn in before on concrete.
A stiff brush on a newish carpet was like trying to control a Rottweiler on heat

Cheers
Doug