One thing up front: the personal benefit depends on very many factors.
I came across the Stage Academy boss Arne Stoermer after a recommendation, as I was thrilled by the enormous development of a manager I knew, whom he had taken "under his wing".
If you want to improve in certain areas, you have to approach topics holistically - and that is what the coach sees and does.
I had several "aha experiences" relatively quickly: things that you seem to know yourself, but which you only become aware of when you are guided to them.
+ Flexibility, professionalism
- Not quite cheap, but worth the price.