Deborah, while I agree with you, I also don't believe that one rodent over another is a matter of connivence not nutritional questions.
I believe there have been studies on snakes nutritional requirements. And there has certainly been fairly substantial (sadly on one level) studies of stomach contents of Royal pythons in the wild and given the counts it is a simple matter to work backwards based on an average. I think that the requirements actually fairly well understood generally and although I don't recall any references to just Royals there are for pythons in general.
Here is a general carnivores reptile one,
http://www.merckvetmanual.com/mvm/in.../bc/171406.htm