IMO, aiming for the spine is not an ethical shot. If the shot is straight down, you will have to go through an awful lot of bone to hit the heart. Too many variables there for my taste (deflection off bone for one). As far as lungs, you will only take one out. Finding a single lunged deer is one of the most difficult tracking tasks that there is. A lot has been posted on that one here on the forum.

Again, this is a low percentage shot IMO.

Where as a double lunged deer should be a 100% recovery.