I dont think it has anything to do with KE, accuracy in the backyard, etc.
If you want to shoot at a deer at 80 yards thats your choice but I think your going to end up wounding more than you kill.
To many variables to deal with at that distance. Wind drift, range estimation, and of course the animals movement/reactions. Maybe if you' re hunting elk on the open mountain or moose in an open meadow.
Then theres the hit. High lung shot, low hit, a little too far back, what? How can you tell at those long distances.
The reason most of the veteran bowhunters I know shoot at Deer at 35 yards or less is because they know the risk of wounding goes up dramatically beyond this range.
If you want to shoot a deer at 45 yards or more, (I dont care how good you are in the backyard), use a gun.
MD, with shooting like you describe, you are obviously in the top 2% of shooters out there. The other 98% of us will stick with fast bows and short distances.[:-]
The squirrels in my area dont stand still long enough for a 80 yard shot.[:' (]