CSeries is the same as 777 with the same C*U. Secondary and Direct are known as PFCC direct and REU direct. FD and AT are still available in PFCC Direct but lost in REU Direct. There is one further drop to Alternate Flight Control Unit Direct. This is completely independent. Starting with it's own RVDTs in the inceptors via ARINC to the AFCU computer which is connected directly to the hydraulic PCU electronic input. Only fitted to one PCU on each primary flight control surface but with a damping signal to the others.Also can drive the stab via one channel for trim. The architecture allows AFCU to be powered by the RAT both hydraulics and electrics. Sim handles pretty much the same in all 3 direct modes if a little less responsive in AFCU. Can't comment on the aircraft handling.