Please contact IATP for permission to reprint. The Pros from Dover . Typically one option is far more costly than the other. Obviously, it helps tremendously if you use the best expertise available to justify your position.
People conducting evaluations vary widely in their skill level.
Some are licensed, others are not. Generally they problem solve by using engineering disciplines, mathematics, physical sciences, life sciences and analysis. If you use a rehab engineer, ask about his or her range of training and experience. A vendor sells equipment for a company or companies. Unless you ask about credentials, you will not know.