I spine shot a deer this past weekend. Arrow hit a twig and took undesired trajectory. I had to get down out of my stand immediately and put another arrow in the lungs to finish her off. I hate having to do that, but that's bowhunting.
As far as a spine shot between the shoulders while deer is under the stand. I've read that is a good shot to take, but I don't know if I would take it. Seems to me it might end with the deer thrashing on the ground for a good bit. To me that is not a desirable shot.