I know that I spined a doe with a Snyper, the Snyper went underneath the spine and one of the blades clipped the spine. She dropped right on the spot. I got down out of stand and walked over to her and finished her. There was a gaping hole below the spine and her lungs where completely unaffected. She was bleating and raising her head and breathing just fine, she just couldn't move. I also think that these hits are very rare. And occur only a fraction of the time that they are reffered to as a no mans land hit. Most of the times it is a poor blood trai/tracking skillsl or bad hit that is rationalized away by the hunter. I also think that the area just behind the diaphram, above and behind the liver, just below the spine is another area, where they're not going to die. And this is a spot where on a smaller animal it might look like a vital hit, but it is further back than is realized.

I think double lung is the best in terms of a quick kill, second would be single lung/liver. But really I think that close point blank shots is what really kills the quickest.