Obi, I can tell you for a fact that on a 737 Longitudinal Acceleration is fed into the FCCs and is used for any autopilot mode or stage of flight that alters the aircrafts acceleration in that plane. ie. Take Off, Go Around, IAS/Mach and Vertical Speed.
All modern aircraft use as much data as possible to refine the flight profile for comfort and economy. As has been previously stated, it's all fed along data buses so it really isn't an issue from an installation point of view.
I'm trying to get your question clear in my head though? When you mean "flight control systems" I take it you mean Autopilots? It may be worth finding a copy of E.Pallets Autopilot book if so, that will tell you everything you need to know.