There's an outdoor range I go to with a raisedshooting platform that's 12 feet high. I don'tgo through the motion of aiming over my target then bending my waist to get on target. But, I can always group. Are you saying that this motion is necessary to hit my target? If so why? Please forgive the novice inquiry.
when you change heights, you are not going to be able to drop your arm the same amount, you will have to drop it more or less depending on how close or how far the target is. So if you want to hunt higher or lower than the 12 foot sight in height, bending at the waist makes it possible to group from different heights. If you always hunt from a 12 foot height what your doing would be OK. but when you change heights impact points will alos change.. the differences you are worried about with the gravity and the vector thing are not enough to keep you out of the kill zone.. what will keep you out of the kill zone are height changes and your nerves when the live target shows up..
I may be wrong but I am pretty sure that using your 40 yd pin on a deer 5 yds from your tree, no matter how high you are is a recipe for a certain miss.
with my set up, on the ground when I am five yards away from the target, I use my 35 yard pin. the closer I get to a target the longer pin I use. when I'm 3 yards away from a target, I use a 42 yard pin, If i'm 2yards away I need a 60 yard pin.
you really need to go close to your target and try this, you will be amazed, reason most miss from a blind close up within 5 yards because they put thier 20 yard pin low on the deer and shoot under it. the 20 yard pin needs to go high on the deer or even above it to hit the kill zone. reason is the arrow travels an arc.