I have two HD 2's. I was planning to use instead of rig mounting my DSLR for drive scenes. However, I thus far have tested the suction cups and arms, and I do not feel like I can reliably use the suction mount. Instead, I plan to use two vacuum mounts, one which I tether to the camera incase of emergency.
Further, I still plan to use the DSLR to get the good ol fashioned rig shots.
Many use
these for their vehicles when vibrations occur during usage.