Well, at least you're not one to rush into decision making!
The Mytee will be fine if you'll be doing 3 cars per week, but if you'll be doing 3 cars per day, you'll want a bigger, more durable machine.
Jimmy Buffit I respect everybody's opinion on this site and what you have said makes sence that you don't want to be just good enough but you haven't put any input on what machine you have or will recommend.
I tend to not use brand names, etc. because I don't want to seem to be promoting particular items... Having said that, in five years, we've gone through TWO Sensei extractors - replaced everything at least twice. (Oh they clean pretty well...) Out of frustration we solicited the advice of local carpet cleaning distributor. These guys sell $60,000 truck mounted extractors, among other things. They convinced me (after a week-long, in shop trial) to purchase the same unit they use in their rental/loaner pool. Made by Northland Products, the
Nexus NP is configured many ways. Ours has the 500 psi pump (which we adjust to 375), heat, and the 2 stage vac. Additionally, we took more advise and purchased a very specialized $250 nozzle. It has been in service for over 18 months now and we could not be happier! The always hot high pressure/high lift system cleans extraordinarily well, and leaves the carpet just damp to the touch.
Almost always, you get what you pay for, and our unit cost ~$2300. Well worth it if you are doing the volume.
Like many other units, it does require TWO 15 amp circuits.
Jim