During a fair landing, I kinda landed on one LandingGear skid and quad flipped over upside down. It wasn't even that bad a landing and really surprised me. Anyway, as it came to rest I heard a cracking sound.
It was the compass puck. So, Prop-Guards won't save the puck. I "glued" it back together with Plastruct solvent.
Installed new double-sided foam tape on bottom. I did a new mount with a Plastruct strap (and small single-sided foam tape cushion) and tiny metal screws.
After Compass Calibration, new Compass Offsets are -118, 9, -1 . One of those is significantly higher than before, but still well within recommended range (-150 150).
Also recalibrated the Accelerometer while I had MP running.
EDIT 2015: Ended-up changing to this mount after cracking puck. Simpler and no extra metal screws near compass. Compass Offsets are a little better now at -99, 17, 15.