VA, I've had the same findings with my set-ups as well. Shooting out of a treestand, as long as you have consistant anchor points and bend at the waist, I don't find that you need to compensate for the angle.

Also, I shoot with a peep.

Now, on a steep bank shooting downhill at a target 40+ yards away (say on a Mulie hunt perhaps) then things might be different... I'll have to check that out.