I am aware that a PR manager helps with attendance. However, the reason I didn't mention it is because he is in div 2 and has a small arena and so will sell out every week regardless of what level PR manager he has (provided his prices are reasonable, although he could probably put his prices at maximum and still get close to selling out).
I have tried using different PR managers in div 4, div 3 and now in div 2 as well, however, I think that a PR manager is helpful when you are struggling to win in lower divisions, or is helpful in division 2 when you have a big arena that you need to fill.
In otherwords, if you are already selling out your arena comfortably, I don't think you need anything higher than a level 2 PR manager.
I notice a small drop in merchandising when I lowered PR managers, however attendance didn't change at all because I was selling out already. And the difference in salary between level 2 PR and level 4 PR was bigger than the drop in merchandising, so I was making more money with a lower PR manager.