if you are targeting aoe's.. accuracy in the virtual world will be dependent on the POV for each wow. if you set them so the camera is on smart follow, and zoom all the way out... the POV should be close to the same as they run (adjust the elevation). if you get feared or channel-turned... forget it. the POV won't be the same until you pull them all back in.

as for flight paths, works every time for me. quests can be a bit different as the quest text will render differently on different sized screens... pushing the clickable item. the complete or accept buttons are always in the same place though