andre w
go research sinners circle. and you have your answer. each method not machine has its overall success. many ways to get to a clean carpet depends on how much time and money you want to spend getting there.
your machine can suck as much as you like but unless you have emulsified the dirt its not going any where.
this subject is about how far away from the wand you want to work. the closer to the wand the less power you need its pressure, heat and vac. start moving away and you have to up these. its that simple. lets not forget all the other methods that can clean a carpet without such a large investment.
good luck