If you are winning most of your games then I don't think there is much of a need for a high level PR and a basic PR with a specialty is fine. However, if you are losing a lot of games, and attendance is a little low, then an advanced PR manager could boost sales and may be worth it.
i must to be honest, i don't understand how the PR is really working ;)
But i thing also the difference theory could be working, if a better PR gives you 1% more visitors you should hire one especially if you are succesful because he would have a bigger impact.