I really liked what you had to say in one of the discussions about not having a feeling for application development until you had been doing it for a while (maybe that's my interpretation of what you said). Is there a watering-hole (on the Net) where people who think this way hang out?!
I don't understand what a SAX event is. To me, an event is something happening at a point in time - in FBP, it's usually the arrival of a data chunk (IP) at a network node, but it could be an external event, like completion of I/O. Also, sending anything upstream is un-FBP-like!
Last comment: most of the SAX:Machine functions have counterparts in FBP, but in a more general way. I don't see a need for special functions like Manifold....