Martin
Like Uncle John, I run Host machines for agitation and, on domestic carpets, I only use it solo. On commercial I've tried doubling up but, to be honest, it can still be too slow so I usually end up using a rotary scrubber. Ultimately not quite so efficient. However, most of my commercial work is now Dry Fusion. I don't like getting involved with too much "Heavy Duty Cleaning" such as trashed pubs and restaurants. That's left for the truckmount boys.
As for vaccing, my preference is for a wider machine similar to the Sebo BS46. The brush on my Victor Gold is of chevron design as opposed to the more common spiral. Being wider, the machine looks more "industrial strength" to the public than one which appears to be of similar size to a domestic model. Perception is a large part of customer building confidence. As for perfomance, you'd be hard pressed to be aware of any benefits of a narrower machine although logic dictates that this should be so. A wider machine can be a little cumbersome in tight areas such as cloakrooms etc. so I end up using the attached tools, but this is frequently the case with a narrower machine too. A wider machine really comes into it's own on larger rooms and commercial premises such as offices, health facilities etc. For really heavy duty work I use my Holloway Pile Lifter.
Safe and happy vaccing agitating:)
Ken