A different POV here...

We are planning our HB, and have engaged our IM, her support MW, AND a doula.

The reasons I have chosen a doula include:
- more 'emotional' support. My IM is fab, but my doula spends ages talking through the emotional fears, hopes, more spiritual side of becoming a mother etc. I am loving this. She has encouraged me to create a drawing-only journal, which has helped me acknowledge and address some of my subconscious fears really well!

- wishy-washy 'care' elements. I love the fact that she will run me a special herbal bath... that she brings flowers... all that.

- At the birth, I want her to take looooads of photos! There is no one else on hand to do that. I also don't want DH to leave me at any time, so she can do any boring things like heating water, preparing a meal etc. keeping him free.

Hmmmm I did think a lot about it. My MW was surprised that I wanted a doula. But I am really happy with the choice. My doula is a lot more into the spiritual / emotional side, whereas my IM is more of a classic, no-nonsense type (which is what I wanted!)