Dual-servo elevator linkage geometry
Mike,
Nice picture (you must be in marketing). However, you are starting at the wrong points. The control arm should be almost parallel to the elevator as a starting point(see original picture). Also, in your example you are depicting crazy amounts of throw. I doubt this plane will ever use that much elevator. If the throws are set properly for this type of plane and the controls are attached as pictured, you will NOT see any deviation and you will NOT have any problems in flight. You are more likely to have deviations from mis-matched servos than the linkage. Even then, it most likely wouldn't show up until you are near full throw.
Mark M.