I think the issue could be easily solved by adding alternate (additional?) personalities to a profile. Then, when posting, you'd add "Markus Persson, Minecraft developer", remove "Markus Persson, default" and voila. No change to circles required, UI could be kept simple and clean, etc. I guess channels are basically the same thing, but depersonalized, and google has/wants to become people-oriented with G+, so name should matter to them.
Or let people attach search terms to people in circles.
Or let people attach search terms to people in circles.