Just my opinion is this but....
Before the trip to India I bought a Touratech mount for my Garmin GPS. Its has rubber mounts between the handlebar mount and the GPS holder so it must be good.
Riding, even on tarmac makes the GPS shake like hell. Most of this is due to the vibrations of the engine (BMW R100GS). At the worst point in the vibration you cant read the GPS, there's so much shaking going on.
There is an inbuilt flaw with these mounts. You cant see the GPS if you mount a tankbag. Useless.
I contacted a guy in the States that makes a solid mount that moves the unit forward, away from the bag. I mounted this bracket onto the Touratech unit to give me more clearance and in the process, removed the rubber bushes from the Touratech mount.
What a difference. The GPS is now rock steady.
Talking to the supplier in the US, I gather that the shocks that could kill your unit are from bottoming the forks. The normal amount of vibes only affects the spring loaded pins that contact the inbuilt battery. The fix for that is to put a strip of tape over the pins and use the bike power.
That's what I did and never a sign of a problem. Solid mounts are the war to go.
Nostradamus Ate My Hamster