Been out of town (hunting
) the past four days. This little issue really took on a life of its own here. I personally don't question the trend for heavier shafts to out penetrate lighter shafts, all other thing being equal. So I guess I believe the general concepts put forth by Dr. Ashby. However, there is still a balance between speed and penetration when considering arrow weight.
For instance, I have thought about using very light 3D shafts for antelope hunting. I'm sure they would penetrate this light boned animal adequately, and the flatter trajectory could be a benefit on the long range shots sometimes encountered. However, archery elk season coincides with archery antelope; and I sure don't want to risk a light arrow on an angle shot at a 900 lb. bull elk. Now that I have a second bow, might think about setting up one of them for elk and one for antelope.
But even for elk hunting, the small diameter shafts - particularly the A/C Super Slims and the Axis FMJ - offer a medium weight arrow with serious penetration.