I don't think measuring the hits on a website would be a very accurate way of measuring a potential user base.
Well I tend to disagree on that seeing that RCU has an RC based user community. Over 140k members and tens of thousands of non registered visitors that come here every month. The statistic is based on millions of impressions, not hundreds or thousands. That's proabably better stats then all the presidential polling for 2004 combined in all the major polls.
Statistically, it can't get any better then that unless you were to combine all of the statistics with all of the top RC forums on the Internet and combine their Mac/PC user data.