One high and one low will result in differential throw to the elevators, with one elevator moving more than the other on certain commands, etc. Think about the geometry (for lack of a better word)....the servos driving off the bottom of the wheel is in the same arc as the control horn, giving a fairly "pure" push or pull as it rotates. The other servo, driving off the top, is rotating downward as the control horn is rotating upward, and will throw less.

Go with the other advice....a reverse servo, or reverse Y yoke if one is available. Or.....do as I have done on my GB Ultimate, which is 9 years old.....one good servo (JR 4031) and a "Y" bass-wood pushrod. Is plenty for that airplane.

Clair Sieverling
AMA 15654