Yes, I have. My generator runs on LP gas, and we put it in with enough capacity to do the whole house. We have had outages that lasted 3-5 days at a time over the lasr few years to loose too much from the refrigerator and freezer everytime it goes out. Once was the dead of winter at below zero temperatures, and twice durinjg the hottest heat of summer!
The newer generators are safe to use, because they are connected to the electric box to supply power to all the fuses for the house.
Yes they have a regulator in the pipes between the LP tank and the generator. It monitors the flow. Here in Illinois your hookup has to pass the power company's inspection for safety before you use it.
Now the gasoline powered generators, I don't know about them.