Hi,
The concept of W' has been around for over 50 years, and yes Coggan incorporated the concept into the PD model in WKO, but it is not at all clear what it is nor how to test for it.The concept of W'bal has no equivalent in Coggan/WKO and is unlikely to.
The concept of iLevels in Coggan/WKO is tying time spent in fixed intensity levels (%age of FTP) to an individuals maximal capability from the WKO PD model. Setting zone boundaries from a PD model is to support workout design -- we have already incorporated W'bal and PD modelling into the workout designer in GC, although always happy to improve whats there. Recommend you look at:
https://vimeo.com/192126358CHEERS
Mark