A lot more then you think. We hooked mine up to a hoist in the shop and with me in the drivers side and lifting the passenger side we were well over 45 degrees and no signs of tipping it on its side. What I have found is on off camber sideways and up hill or down hill the teeter totter effect was unpredictable
I agree, testing with the machine level front to back and slowly lifting is kind of a static load as compared to real life dynamic load that has momentum as it pitches especially if the machine isn't level front to back. Just thought it might be a handy tool to help calm some of the fears (and screams) coming from the passenger seat.
That actually looks like a neat idea. Every time we get anew machine I always take the wife with me or have her drive it up on obstacles at our house to get here used to the angle so she knows where she is still OK and not going to tip. This device would certainly create a more repeatable visual indicator. I have never seen anyone use one before, but seems like a good idea.
Alot of companies make them just for off road vehicles and you even can get a app for your smart phone that does the same. I bought one because I have a couple of very steep hills on the property. Always wondered what the incline was.