RE: servo/boost tabs
Actually boost tabs are a lot of work And I think just getting the proper torque servo and good linkages are the way to go.
But, if you can't get a servo with enough torque it is a method to try, I think the range of deflection they will work at is governed by the control linkage geometry.
Wouldn't it be a lot easier to set up dedicate trim surfaces if that is what you wanted?