I post the majority of my stuff to the public stream, because I use Google+ like Twitter except without the limit on what I want to say, and a much better interface for conversation.
I also post the majority of my stuff as public. I suspect that my "Limited" circle posts will pretty much always be less than 10% of my posts. That might lead some people to believe that the circle feature isn't important since I'm using it only occasionally, but that would be a very misguided and wrong conclusion, it is still very important to me that the feature exists for when I do want to use it.
I broadcast into the clear and receive the circles I want, except for that one time when I may have something just for a particular person. Not sure I'd want to be receiving just a selected broadcast from someone 100% of the time.