They do cause some body "twist". At least on my Explorer it has. I have a 3" and when I needed a new windshield put in all the glass shop had to do was push the old one out. They used a little different stuff on the new one, so hopefully it will hold up. There is not a lot, but some.My dad has said it causes the body to bend and things like that. I'm not really sure if that's true or not.
The only real pro, is they make more room for bigger tires (and in some cases room for other mods, my Ranger has a 347/C-6 combo and everything fits pretty snug).