Hi Thane,
There isn't enough there to go on. Species and load per peg would be the starting point using this method. You seem to be basing the spacing distances in your first pic on the peg diameter? If so that is not my understanding. My gut reaction looking at that joint is that I would scratch my head and call it good.

I have been rereading the translation of the German oak peg studies in the green book, I hope that is the pair of articles you were referring to. Reading those and especially Dick Schmidt's conclusions at the end of each article has helped me see how I think the thought process has been developing on this.

I've been lightly reading the tables in the article, metric makes my head spin. Table 3 in the second article looks like a gold mine. I'll try to convert it and do a little ciphering to see if it agrees with what I think I know.

I've also been reading these papers for more background;
http://www.ewpa.com/Archive/2004/jun/Paper_202.pdf
http://www.ewpa.com/Archive/2008/june/Paper_181.pdf