No ivars -> What am I missing?

Question

I never use ivars. I only use properties -- sometimes assign properties with primitive types, and sometimes on a "private" class extension. I've seen the advantages of not using ivars in switching to ARC -- I have some borrowed code with lots of ivars that I still can't "ARC", since I don't know what needs to be retained. So I know some advantages of not using ivars, but what are the advantages of using ivars instead of properties?

Note: I depend exclusively on the ivars that are automagically added in (by the compiler?) for the property declaration.

Don't mark to close: I've looked at some of the other questions, like this and this and none hit the spot. The titles look good, but like so many questions on SO, the questions are a mess of strange doubts and other stuff.