Dave,
DON'T go into commercial carpet cleaning with a padding system! Why? Because you will severely limit your business opportunities. Padding systems do work well on low profile office carpets but that is only part of the market. If you want to be able to sell your services to the wider market you will need an RX, you will also need a somewhat more powerful Truck Mount than a Prowler (sorry john)
Commercial cleaning can some times require long hose runs, cinemas, office blocks, shopping centres etc , if you can't reach them you can't do them.
I suggest that instead of picking a machine first (which is what you appear to have done) have a sit down and think out where you want your business to go in the next five years and then get the equipment that can take you there.
If you need any help in that let me know.
Simon