I've used CFR machines since 1997.
Like everything, there are pro's and cons.
The tools are fantastic and you get a lot of power for a portable. You get outstanding results on upholstery. Drying times for carpets are low.
I always use a prespray and then clean water (occasionaly acid rinse) to RINSE with.
Maintenance is vital.
The machine (particularly the pump) are washed through at the end of each working day. Since I have been using M - Power, this has been more necessary, due to a very fine film building up on the internal filters. Again, these are cleaned each time.
The machines are great for most jobs.
On grubby carpets (e.g. pubs), you are going to quickly reach a point where the filters start to clog (despite the self cleaning features) and like it or not, you will need to change water a couple of times. This will be less than normal porties though. I normally use a self contained machine with integral brush for grubby jobs.
I saw a nightclub being refurbished the other day and the contractors were using CFrs with the hard floor wand to clean a large tiled area.
Overall great results, as long as you are willing to do the necessary basic maintenance.
garry