Agreed, it should work, but the wideband isn't hooked up to the dyno at all.That does read back to the dyno. A competent dyno operator will log afr while making a pull regardless if they are making changes to the vehicle or not. The AEM is the cheapest and easiest to use.
Is there an AEM model that you recommend that does logging? I see several models but for tuning i think one that logs will be more effective.