I'll know soon enough Jerry. There's a couple of high speed trails in my AO that bounce the faceplate off my radio.That long arm length sure makes me think it'd shake and move around too much on a rough bumpy trail. A friend has a short very rigid aluminum design that clamps to the glove box grab bar with no movement/bounce at all on bumpy trails. If I ever get a tablet that's how I'll mount mine.
Right now I'm more worried about where the base plate is attached. I sticky taped it to the side of the center stack. That's much flimsier than expected. If the arm works as expected, I'll fab up a bracket to tie into the sheet metal under the dash. The mount itself is pretty stable. No movement on the street so far.