Ive seen this happen not once, but twice. Once was an GMC 2500 and the other time it was a grand am GT.
The 2500 fell all the way from the top. The tech didnt set the rear arms right and they just kicked out, and the fronts went up into the wheel well and just about ripped the fenders off the truck. The grand am went down when 1/2 the hoist failed, it landed on a rather large oil change catch drum and split it down the side. I would estmate that it spilled 30 gallons of oil under the fallen car.