4 post lift vs. 2 post lift. Pros and Cons.

I always liked how 2 post lifts gave so much open access to everything.
Yeah, I like that too. How do you balance the vehicle? What I mean is how do you determine the center point of the weight?Are factory jacking pads engineered for centering a vehicle's weight? I get nervous thinking about a car crashing down when pulling or pushing under there.