RE: CONTROL HORN LOCATIONS FOR PULL-PULL SYSTEMS
N1, it makes perfect sense. Regardless of different lengths, both sides of the servo arm move the same distance in opposite directions. It will pull the Control horn the same distance in opposite directions. If the Servo arm is smaller than the control horns, the servo will rotate more than the total rotation of the control horn (In degrees) but the distance traveled will be the same.
You can try a quick little experiment if you like...
Get 4 balsa sticks. mark one of them at center, and at 1" from center on each end (The length isn't critical as long as they're even) Mark another at center and at 1 1/2" from center. Pin both to your workbench through the center mark so they can pivot. Then join the ends with the two remaining sticks by putting a pin through the outer marks. Pivot the smaller stick, and the larger stick will follow.