I decided to buy the Leica Handgrip M for my black M9-P and I definitely like it. The handgrip in black has exactly the same texture as the M9-P and fits optically perfect.
It replaces the normal bottom plate of the camera and has a tripod mount as well positioned at the center. Overall what I can say is that the camera feels much more solid in your hand. Though it is a little bit pricy at € 220,– I would highly recommend it if you are searching for the extra stability – especially when capturing in portrait mode.
Let me share some pictures of the M9-P with the handgrip attached.