Are you talking about the danger in winching or in jack use or both? I hope I never have to use it as a winch but its a great option if your alone and dont have a winch.
I'm talking about using it as a Jack. You open a whole separate range of safety observances when using it as a winch, but in general, people seem more alert at such times.
The key to safe HiLift operation can be summarized as follows:
1. Set base of jack a bit closer to the vehicle, so that the top of jack is angled away from your sheet metal.
2. NEVER take your hand off the handle unless it is in the vertical position
3. Your hand on the jack handle should be facing down, with positive pressure to prevent it from pumping on its own should it decend.
4. NEVER hold the jack in such a way that your fingers can get smashed by the jack handle should it decend quickly, making the handle pump up and down very quickly and forcefully.
5. NEVER put your head anywhere inside the arc created between jack handle and top of jack. That handle will break your jaw or worse.
Here is a photo of the right way:
Here is a photo of the right way to set up a self-winch using the HiLift. Takes about forever, but it works.