I have never used Grizzly's, but have been following some of these threads lately. I think what Bob said is right on the money. I don't think alot of this really applies to most of our NA animals, and especially not deer. Following 6-point's line of thinking, how much farther does the arrow need to go after passing through the deer? I'm all for trying to use solid, quality equipment, but I think this attitude of wanting every advantage sometimes blinds people to the fact that there is a point of diminishing return.
None of what I am saying is meant to take anything away from Dr. Ashby's excellent work. If I was planning a trip to foreign soil to chase the big critters, I'd most likely follow his advice to the letter, I just don't see the fuss when talking about our comparably dainty, whitetailed deer, or similar sized animals.