RE: Long servo arms or short control horns?
Blazer - I understood you the first time. you are correct in that it is the ratio of the two arms that determines the throw. to extend your example, you could use a 2-foot servo arm and a one-foot control horn. The advantage of the longer approach is that the axial forces are lower.
In your example, suppose you had a 1" servo arm and a 1/2" control horn and you measured the axial force in the connecting rod. Let's say it is 6 pounds of force. If you go to arms that are twice as long, then the force in the connecting push rod is only 3 pounds force. So the connecting rod does not have to be so stiff. Also suppose that there was 1/32 inch of play (slop) in the connection. With the longer arms, the 1/32 play will not cause as much deflection of the surface as compared to the short arms.
So longer is better than shorter. on a 35% scale aerobatic plane you typically see 1.5 inch or two inch servo arms, for example.