We have used what is called a 94% ergonomic model for our development. That means that 94% of all people will have a secure fit.
Beyond that, we have no cable tugging at the headphone, and the center of mass is inside the ear. The Dash will always touch 3 points in the ear, if the right size sleeve is chosen.
We think we have a great solution, and it worked with 48 out of 50 people that tried them in our ergonomic tests.
Every ear is different, we have tested long term ergonomics and have very positive feedback.