Having the arrow remain in the animal to let the broadhead keep cutting as the animal moves is an old concept, but I couldn't tell you for sure if it really works that way. Is the broadhead actually causing more damage or is it just an urban legend? It sounds plausible, but who really knows?
I think having the arrow sticking out the side of the animal as it runs, slapping against the brush, will just keep spooking it and make it run faster and further. And I like the idea of having two holes leaking. I want the passthrough, but as long as the arrow's in the right spot and does the job, I'm not gonna gripe if I don't get it.