IIT treats any difference in Φ as significant, so even CAS with minimal difference in Φ will be entirely not conscious
...but IIT predicts consciousness would flicker off as soon as Φ of the supersystem surpasses Φ of your brain.
IIT correlates Φmax with consciousness. Since ΦA and ΦB are equal, neither A nor B have Φmax. Therefore, IIT predicts neither system is conscious despite no change in complexity, Φ, or function in either system.