The VogelPullz have to be my favorite assistance movement for deathlifts, but, this movement is only a once in a while type of movement. Its very hard, you have to stay extremely focused while doing it because you can fuck yourself up very easily, and it takes a toll on the body. I will do this movement about once a month or so. I love it because it totally destroys your entire rear chain.
My favorite practical movement for Deathlifts would have to be the pin pull, preferably with heavy band tension. With the heavy band tension you have to exert a lot of force and speed to get the bar moving. It really teaches you to strain. Your lockout will be bullet proof.
Against band tension:
Without band tension: