Great results. I have been working very hard with some of my websites.I was never promoted above PR1. You have PR4 and that is lucky. Good PR means you have every chance to reach large number of audience. It adds quality. Happy for you .. Keep it up
My sites 2 years old with over 1600+ back links yet it is still a PR1, I don't get it. Another site I created which I sold was only 3 months old had a PR2..