Reality backs this up, a stunt pilot more or less decapitated himself with a heli a while back and while I've seen plenty of rough multicopter injuries ranging from bruises to lacerations I'm not aware of anyone who has managed to kill themselves with one... yet.
The tip of a single blade helicopter has much more energy than the tip of a roughly 1/4 radius of a quad-copter blade.
Despite the complexity, if the copter is large, I would think there's much less liability baked into a quad-copter.