I just got on line a little bit ago and saw this. I'm so sorry, I have two cats and I do understand. Hopefully by now he is curled up in your lap sleeping but if not try not to lose hope. You said you tried making "feeding time noises" but does he have a favorite toy or something else like a treat can that you can shake that he might reconize?
It sounds like you have done all the right things by calling the human society, posters and talking to neighbors. I hope if he isn't home yet that you will find him soon. My heart goes out to you!! Hugs!!
-------------------- Taking it one day at a time.....