I'm still not on board that there will be any enrichment at WOT, but I'll have to wait until these dyno results (if the OBD-II data is given) or when I get a chance to drive my wife's 4Runner. I tested my Prius v today. Closed loop under WOT with fuel trims still active. Not exactly a direct comparison to the 4Runner ECU strategy though.
There will certainly be no enrichment at part throttle. A constant power or load comparison would be nice. If it gives you 3-5% at WOT due to leaner combustion, part throttle gains may be negligible. I imagine most of us run at part throttle >99% of the time.