Beats me.. I just posted that as an alternative solution.. especially for the flutter problem when you have all that mass hanging off two sets of hinges as in Bruce's variation..
Aerodynamically making the middle part the support stiffens the structure, while not affecting the controliability... I think.
I've used a boost tab system on a flying tail, but only the trailing edge flap moved as the slab itself was moved by the servo.
About like Bruce's drawing.
Put it on a foamie and try it... ???