It's not the shock mount, it's the fscking, that concerns me. I trust the hardware.

I trust neither, and I especially don't trust that the power will be there from the beginning of the write to the end of the write.

But if we're talking about just unlocking /programs0 to write one file and the locking it again, I don't see a problem with doing that as long as it's user-triggered.

I would be perfectly happy if there were a menu option in GPSapp that says "Write data to disk now", and when I hit it, it saves everything all at once: Track history data, almanac/ephemeris data, whatever. It would then indicate when it was done on the screen somehow.

That way, if the data was important to me, I could make sure to do it and be sure it was done with the write before I turn off the ignition and pull the player out of the dash. And only when the car wasn't going over bumpy roads.