If you want to get an idea of how much the high volume players play in rake, and how common they are on the various networks, you could easily buy enough hands to get a pretty accurate picture from some of the datamining services.
I won't get into the ethics of buying and selling hands, but it is pretty common place among serious players, and could get you a quit accurate way of keeping a tab on where the high volume players want to play. But if you are targetting those guys, you probably know it already
