In any case, Dan, it's hard to see how you're going to be able to write anything but a purely anecdotal account of whatever supposed effect you may hear of. There's not going to be any source of non-anecdotal information that covers more than a tiny number of the thousands of golf course out there.
Anyone seeking to demonstrate that high rankings make money is certain to find some course somewhere who charged higher green fees or brought in more dues after a ranking upgrade. Anyone seeking to argue the opposite can just as certainly look around until they find an example of the opposite.
Any "study" that you come across is either going to purely polemical using a small selection cherry picked numbers or else it will purport to answer the question more generally in which case it is surely a misrepresentation of the actual facts available.