Val, none of those are published, peer-reviewed academic studies. The Ecoliteracy packet sounds nice but you must know that they're sort of spouting off and that their endnotes are not rigorous. The first one you link to looks promising, but they have not published anything yet. These are their preliminary results and they seem to be focused on BMI: http://www.agatstonresearchfoundation.org/HOPS_Study_Preliminary_Results_HOPS_1_and_HOPS_2.pdf

I actually follow this general subject quite closely for work and I really don't think anyone's come out with anything major on this WRT performance. You say "just do a Google search" as though one is going to come up with lots of solid science on this. You will come up with lots of people making conjecture, sure.