Is it really needed???

I am in the process of putting all guages and computer software into my car. My firend is telling me that something such as the dynojet wide band commander is necessary for air/fuel and data logging. Is this necessary since I just ordered the pms system? I know the pms is more for fuel but would the software such as the dynojet wbc or innovative lm-1 be necessary?
 
It wouldn't be a bad idea. If I were to spend $1000 on an Anderson PMS, I would spend another $400 to see exactly where my A/F was, ESPECIALLY if I were running boost or nitrous. Other than that a good ear and plug reading would probably be OK.