Hi Dave,
I am not sure which side of the line you rest on, but I will sign off with this -

I have a friend who has flown F2B since before I was born, and he directs me to use a prop load lighter than heavier (typically in pitch),
And another who has hand built hundreds of diesels and fixed probably thousands in his life time who tells me that more engines have been ruined by high prop loads than any other cause.

Also every engine manual that I have ever read directs me to use a low load and vary that during the break in time.

Now how does one prove that one way may be better than the other? You would have to invest thousands of man hours and compare like to like in order to gain any valid comparison and even then its either at the end of an engines life, where longevity becomes apparent, or outright power figures that need considering.

And temper this with the urgent need to simply get that engine initially running and its not hard to see that a large diameter prop is chosen.

So its easy to see why some recommend a diameter and pitch within the engines operating range but within that range you have a choice - choose wisely.

As a final endorsement please checkout - http://www.eifflaender.com/instruct.htm and note well the smaller prop sizes used for run in.