It would seem that an arm at each would be better than a wheel at the servo and arm/horn at the surface..right? The 2 arm setup would create the most similar geometry as the attach point of the wire is traveling through a similar arc at each end. With the wheel, that point always stays at the same tangent point, creating the true linear pull while the other end travels through an arc causing less linear pull distance????....help....I think i is cornfused..