My personal view is that fitting a parachute system to a drone will be of limited benefit, particularly if the drone is flown below 400'. The opportunity for the parachute to fully deploy to successfully prevent damage to the aircraft will be tight at best and will depend on certain factors in the nature of the aircraft's 'plummet'. Indeed, even at higher altitudes, there needs to be certain factors in place for successful deployment, for example, it all to easy for the parachute to become tangled with the props/arms.
Of course, this is just my view. Others will prolly see it differently.