Won't affect resolution or torque (current drain), since linkage ratio is same (surface deflection and servo travel both cut in half).

Will improve resolution and reduce torque/current, since linkage ratio is reduced.

2nd option is the way to go!

But the linkage should be changed by moving the pushrod attachment point on the control horn outward, NOT by moving the attachment point on the servo inward.

Yes, agreed, but that means we can't also strive for the shortest servo arm because that would alter the linkage ratio, which changes the surface deflection.

I choose pushrod attachment points like this:
1) Decide amount of surface deflection needed, then
2) Attach pushrod to the outer hole in servo arm, then
3) Attach other end of pushrod to whatever hole in the control horn provides the desired deflection (for me, usually the outer hole or next hole inward).

A long control horn (which forces using a long servo arm) reduces the effect of linkage slop AND reduces pushrod force, while not changing torque anywhere in the linkage setup AND not compromising resolution.

I agree that using the outer hole in servo arm worsens the effect of servo backlash, but (at least for me) linkage slop is always greater than servo backlash. And pot resolution will not be compromised by using the outer hole because, as long as the linkage ratio is maintained, the travel of the servo stays the same.

That's why I emphasize John B's post - because it's not immediately obvious. In fact, I think many people avoid using the outer hole in servo arms, believing that it will cause higher torque load on the servo or reduced resolution.

What limits the length of servo arms and control horns? Offhand, I see 4 things:
- Width of fuselage
- Pushrod routing problems
- Drag from large control horn
- Ugly appearance