I have tried multiple yolk and window mount devices for my iPad Mini and was unhappy with the results. Had a problem with the yoke mount option partially obscuring the flight instruments and the window option not in a user-friendly location. I love having access to the iPad on the knee board. I can easily flip to my checklists and reference material already on the knee board and still have quick and easy access to the iPad.
The only small complaint I have is that the iPad lies completely flat on my leg. I added a small lift device to the back of the holder for better viewing.