Well, not sure if this will help or not but I have similar Link Exchange progrma running on my other site with different orientation. Site is online since August 8 and currently revieves a PR4. My gambling site for which I’m offering link exchage is a lot better optimized since this is my second site build on same technology.
Here is an site I was talking about: http://www.free-secrets.org just click on Link Exchange. Browse through the site and you will see that PR is fairly consistent throughout the site.