There is no doubt that all things being equal a two blade COI head will outpenetrate all other heads. Does this mean they are the best? Not necessarily. I have found that three or four blade heads produce better blood trails. Also unless you are using some of the heavy duty COI heads like the 190 grain Simmons Interceptors they can bend or break with heavy bone contact. I shot a deer 3 years ago with a 100 grain Steelforce and it completely shattered after passing through the ribs on the right side and hitting the offside shoulder. I recovered the deer but there was nothing left of the head but the center ferrule. I have never had a 3 or 4 blade Muzzy do that. Besides penetration with a fixed blade head should be a non-issue with anyone shooting a modern bow of 60 or more pounds and over 27 inches in draw lenght. I' ve read a lot of Dr Ashton' s study but it seems as if its geared more towards game larger than whitetails. If I ever go after a Cape Buffalo in Africa I will heed his advice but for whitetails I think you are better off with more blades and a trocar type tip.