Good stuff Randy.I have no idea which does the best job, but I think they're all fundamentally flawed. I call all of the above carpet cleaning toys. To get enough vacuum, heat, and water pressure to do the job right on all carpet types I doubt it's even possible to build a machine that can be bought new from less than 100. to maybe 500. With weak vacuums, very, very low pressure, and virtually no heat all these machine are good for is a temporary appearance boost which normally last a few weeks or days. In just the past couple years I've cleaned for at least 2 women who had serious residual moisture problems caused by trying to do it themselves. One eventually replaced the carpet. Oh, and lets not forget just how quickly most of the above machines will wind up in the trash pile.
Btw, I just got a good lesson on just how hard it is to clean carpets with very low water pressure. Lets just say it CANNOT be done even with a truck mount!