The key principle to remember is that angle between thevector representing gravity's effect and arrow's direction of travel is less than perependicular when shooting upor down hill. Therefore, gravity's effect on the arrow's trajectory is less pronounced relative to the line of sight on uphill/downhill shots.

In other words, when you're on level ground, gravity acts perpendicular to the line of sight and the arrow's direction of travel. So, it's affect is most pronounced.

With bagem's formula's you can see that the effect is minimal with most tree stand heights - especially if you maintain your form and do some realistic treestand practice.

Is this horse dead yet?