IMC controller - What reference model should I use?

Question

I'm going to build an IMC controller, Internal Model Control.

The Forward Model is the reference model. If the Plant and the Forward Model is identical, it will result a zero value to the Feedback Signal. But in reality, the reference model is not identical as the plant model.

So my simple question is: How should I design the Forward Model?

1. A approximation model of the real system by using standard transfer functions templates? Example: First order, Second order etc.
2. A transfer function as Forward Model which has been created by using advanced system identification?

Can I interpret an IMC controller as a disturbance compensator?