I think I understand your question- by refering to a horn that mounts further from the hinge line, do you mean like the DuBro heavy duty horns (as opposed to a conventional nylon horn that screws into a nylon backing plate)? If that's what your asking, it depends on a couple things. For example, I assembled a Skyshark Edge ARF that had ailerons that did not lend themselves to correct positioning of the horn pivot holes directly over the hinge line. To do so, I would have had to let the nylon horn protrude into the hinge movement space, interfering with the range of motion. As a result, I had to move the horns a little further away from the hinge line to get full range of motion.

If you use the horns that mount further out on the control surface (like the DuBro HD 6-32 or 8-32), there is no danger of the horn interfering with the range of motion like in my previous example. If there is a small "footprint" for the horn mount, install a hard point so the horn has some solid material to torque on. You don't want to mount a small footprint horn in soft balsa and have it flex and eventually damage the surface and get sloppy loose.

GP and DuBro both make some heavy duty nylon control horns of the conventional "sandwich" style too. They are pretty bulky, but work well.

Hope that helps

Here's a link to the Dubro horns I was refering to: [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXEMF9&P=7]HERE[/link]