S-parameter circuit model extraction is usually characterized by a trade off between accuracy and complexity. Trading one feature for another may or may not affect the goodness of the reconstructed S-parameter data, which are obtained from frequency domain simulations of the models extracted. However, the ultimate test for the validity of these equivalent circuit representations should be left to eye-diagram simulations, which provide useful insights, from an SI point of view, about the degradation of the signal, as it travels through the system. Physics based simplication procedures can be used to tune the models and achieve less complexity, whereas the comparisons of the eye-diagrams may help to quantify the goodness of an these circuits extracted. In fact, the most accurate model is not necessary the best to be used.