Make sure you lube/WD-40 the Hi-Lift jack before every use/trip. One time mine seized up on me in the "up" position. I called Hi-Lift for help and they told me to take a hammer to "tap" it.. which swung the handle up with enough force to break my jaw if my face was 2 inch closer.. which is the reason why it can be dangerous, and why you should ALWAYS stick a big rock (or at least the spare) under the truck BEFORE going under it -- if you're using the Hi-Lift to suspend the truck.
Still, I would never consider off-roading without it. At Rubicon, I blew a bead while my truck is downhill & sideways, wedged between big rocks, in pitch darkness, and freezing temperature, with both of my kids sleeping in the back seat. Without the Hi-Lift (and H2Rocks
), I don't think any other recovery device could get me out as quickly, safely and without any damage to my rig.