New controller or old PLX controller. The new one is tiny... Seriously, it's small. You could put it behind the gauge in the pod if you wanted. Mine is in a location that makes it easy to service and add onto, especially since it feeds directly into my AEM EMS 2.
In addition to virtually finding no gain (unless you have an ISSUE), you'd be better served adapting an ECU that just gives you full control over each injector and individual cylinder knock correction. Having a proper flowing fuel setup to begin with and a solid tune (to include timing and knock control) would go MUCH further.
However, I still stand on that you would be MUCH better served with an EGT in every primary port vs. a WBO2. In either case, in a situation like this, it's a gigantic waste of money with either route. You can use logs to get an idea how it's running. If you're having issues you cannot figure out, pull the plugs.
The cylinder would not have to run lean or rich throughout the entire rev range to see a spike in a log, which is the only way you're going to be able to process that much information anyway. The time involved would be astronomical to nail down and/or far more money than it is worth.