Programs such as VBS's Professional Output Manager are designed to run on your Mac or PC and using the computer's resources and speed, take Postscript data, and output to your film recorder. POM is available for virtually any film recorder on the market. Prices run even higher for high end Management Graphics and Agfa systems. After that start thinking Postscript. If you are a service bureau or centralized in-house service, you may need maximum speed.
Most users can get by on less.
Consider the busiest times - Film Recorders often sit idle and then are heavily used for a few days. Remember that the computer's speed is an integral part of overall throughput. Probably will not be the biggest factor, but it does make a difference. That's close enough that it's probably not wise to buy a particular system just because it's a little less. You have to live with your decision.