Doug,
All EPAS units have an integral load sensor. That means the motor is off until it senses a load, such as when you turn the steering wheel. The motor then compensates and gives more or less assist, depending on the load. The potentiometer or VSS only sets a limit to that assist. I don't believe an EPAS unit can tell how fast the car is going, other than loads are typically greater at lower speeds. Unfortunately, that's not always the case.
The two "strategies" result in a very different "feel" for the driver. Gerry R. can describe these differences to you. I can only tell you about my own experience, which is with the EZ system. It never feels like power steering. At normal speeds my steering feels exactly like it did prior to EPAS installation.
DC Electronics has one EPAS system where the motor and load sensor are separate, for installations where space is very tight.