Add extra features sparingly, only adding those you know you will use. If the Pro's are sure they will use the machine for teaching, get a wireless remote. If you know that you will have a significant number of advanced players using the machine then add spin control. Downtime is a program killer. Make sure parts are easily available.
Many machines are very modular in that it is easy to swap out parts when they go bad.
The key here is buying a machine from a manufacturer that makes it easy to talk to a person quickly if there is a problem. All manufacturers offer and 1 year warranty and some even offer 2 years but the reality is that most problems do not occur under warranty. That is why it is important to go with a maker that has a reputation for longevity and reliability. Reliability is not sexy like features but it is the heart of your program. Always put it at the top of your list.