The sensors looks the same was all I was saying.
The sensors themselves are the exact same. The difference is that How the ECM interprets them them.
The computer monitors the 1st O2 sensor for fuel trim, it uses it's reading to adjust injector pulse width during closed loop operation to maintain a nice clean 14.7 to 1 air fuel ratio.
So basically anytime except for WOT the ECM is watching that 1st O2 sensor to make sure the AFR are spot on and that is all it does.
The 2nd O2 sensor is solely for emission monitoring. The ECM watches it to make sure it doesn't have a matching or similar waveform as the 1st sensor. If the 2nd O2 looks similar to the 1st then the ECM throws a P0420 because the catalytic converter is no longer doing it's job. This is the only thing the ECM monitors the 2nd O2 sensor for and will not adjust fuel trims based on it's reading.
Now whether Vince can get the ECM to swap duties and use the 2nd O2 sensor for fuel trim correction, I don't know. I kinda doubt it but I don't have the intuitive understanding of the ECM to say with any certainty.
It's something worth checking into.