Weight and altitude are the problem with the chute. This thing would result in a fatal accident at low altitude with power loss (total, they say it can operate with some systems lost) that are too low for a chute to deploy before you hit the ground. A similar problem exists with many ejection systems for military aircraft (pilot will escape the aircraft if it's on the ground, but not reach sufficient altitude for the chute to help when they return to the ground). Helicopters can auto-rotate, allowing for degraded performance during the descent but still controllable and survivable.