IMO... The first picture in your first post is pretty darn close to what I would call ideal. Assuming the hinge line is at the top of the control surface, If the rod were extended just a bit it, the pivot point ON THE ROD and the hinge line would form a nice 90 degree angle to the rod. That would give equal throw each direction. I've gotten caught in the trap that the push rod pivot point has to be at a 90 to the control surface. It does not need to be. If you took the picture a step further and moved the servo directly below the control surface, the pivot point of the rod would be above the control surface, again assuming the surface is hinged at the top.

You can simulate this with a couple of pieces of balsa on a piece of wire. One will be the control surface and the other the control horn. On the horn use a stick with a pin to make your push rod. With the control surface staying in the same spot relative to the rod try moving the control horn around the rod keeping the push rod at a 90 degree angle to the control horn. You will see if the horn/rod relationship is always 90 you will always have equal control movement. No the only question is "where do i hang the servo?"

This makes sense to me, I hope everybody else see's what I'm trying to get at.

Ken