I have never known anyone who had one collapse. A collapse is to fall down suddenly as in a structural failure. These lifts were originally developed for wrecking yards and designed to be portable. Like you I seriously thought about buying one 6 years ago now but performed due diligence and compared the lift to similar equipment specifications that we were installing at the plant we were then constructing. Offset lifts like this required an underground cage with a special concrete mix. Very expensive to build.
After speaking to Engineering I was thinking to do it I would need a minimum 6 inch thick floor with re bar reinforcement and Footing Keyways at anchor locations. Meaning I would have to tear out my perfectly fine 4 inch mesh reinforced floor and re-pour it.
The problem with the Offset design is not side to side motion but front to back stresses. Front to back motion is what has to be prevented as once it gets rocking at a certain point basic physics will take over.
I concluded it could be mounted safely to where I could sleep at night, But the cost to do so would likely exceed the cost of about any other lift on the market.
I ended up going with a 4 post with good locks. Even with that If I am putting a car up on the lift for storage I will strap it front and rear to protect in the event of a typical Ohio style earthquake that we have from time to time.
Here is a guy doing modifications to his floor for a two post.