A burst balloon in near space quickly deccelerates and starts its free fall down. In about five seconds, the near space craft will reach its maximum speed and have fallen 500 feet (based on data from flight NearSys 09D). Video footage shows the parachute opening and closing and the remains of the balloon whipping around. Its very traumatic and its accompanied by lots of jerk (changes in acceleration).
A BalloonSat not properly designed for the post-burst chaos is liable to open up or fall apart.
To test for this situation, tie cords to a broom handle and suspend your total BalloonSat (batteries included) from the cords just like it would be suspended from a near spacecraft. Hold the end of the broom handle away from your face and give the appartus a good shaking.
If your BalloonSat holds up, it's ready for the balloon burst and descent.