I agree with WV Hunter.....the difference does not affect arrow flight and anyone who shoots enough competitive 3D knows this.....either down out of a tree stand, or up a steep hill....you aim exactly where you intend to hit as long as you bend at the waist..

Archers who claim you have to aim low are not following proper form. They tend to stand upright and drop their bow arm down changing the sighting plane/triangle from their bow hand, arm and eye....Do this experiment....draw your bow in your house...while at full draw, twist right and left and then bend at the waist and pretend to shoot down or up...you notice the difference between your bow arm, eyes and sight stay consistant.....now don' t bend at the waist but drop your bow arm, this same triangle between your eyes, arm and sight now changes drastically...this is what causes archers to shoot high and miss.

The only logical reason to aim low would be for animal reaction.

Like someone has in their signature......AIM FOR THE EXIT HOLE...aiming for the far shoulder is also a good idea...know where you want your arrow to exit and give it to them.