Think About It
77-
So, let me get this straight. You actually believe that if the AFCS/SAS were to immediately go offline while in high speed cruise, the t/r thrust will somehow cause the aircraft to immediately roll? Kind of like a loaded spring that is released? That the AFCS is normally counteracting?
The AFCS TRIMS the aircraft controls to the current flight condition. That is, the t/r is providing the correct amount of anti-torque for trim coordinated flight. (Which by the way, is not all that much due to the sizable aerodynamic anti-torque.) So while the the aircraft will quickly be marginally stable and very "loose", it certainly is not a wound up spring waiting to flip you inverted. The inverted flight comes later, from the pilot's inability to fly the unstable dutch roll mode.
Do you not practice non-augmented (sas off) flight? I suggest you do so. How do you know your skills will allow you to fly the aircraft after a dual SAS failure? Remember, the aircraft is certified VFR SAS OFF up to Vne.
Hoss
Also, The -76C++ DECUs do indeed use Nr in the control laws, but close the loop around N2 in normal operation.