The most cost effective and versatile piece of equipment you can have is a rotary machine.
I prefer a 230rpm 400mm Victor, but the industry standard is a 175rpm 450mm.
On larger jobs you can go through a lot of pads, so it may be worth your while looking at Super Pad Charly from Alltec or the microfibre pads plus a scrubber from Solution UK. With the M/F and Charly's you need just two pads. 1 to use and one soaking in the bucket.
I use synthetic pads now 'cos they are easier to launder afterwards, but cotton are useful to have for drying assist with extraction jobs.
I've cleaned acres and acres of carpet with generic bonnet cleaning and for me, the best products have been microsplitters, M Power and more recently DFC 105.
Lots of CC's are now working with Encap. I've a little experience with this but to be honest I've not enough experience with it to offer constructive comments about solutions, but I did find on one job where I had lots of different kit to play with, ie CRB, 230rpm rotary, 290rpm rotary, 175 rpm rotary with bonnets, pads and brushes that the 290rpm machine with a white floor polishing pad gave the easiest results.
Safe and happy cleaning
Ken