I always thought pass through, but after talking to a elk guide this past weekend he almost has me convinced that a fixed blade broadhead is better to stay in because it does so much damage when they run.
And RUN they will. Quite often when an animal is shot he jumps at the sound but stops after a hop or two to look for the source of the noise. We all know that a hit in the vitals is pretty much painless. That's been discussed over and over in papers by biologist and doctors. BUT, I say that if that arrow is in there slapping around and smacking on trees as they flee it just pushes them harder and faster. I'd rather the arrow slip through both sides of the rib cage and stick in the ground. Much shorter tracking job to my way of thinking. Make an animal run faster and faster with an arrow smacking him in the butt he'll spread the blood a lot thinner than if he were just taking a few bounds and not running in BLUR.