I think that open allocation in terms of project mobility is the right way to go. I also think that flat structures are rarely truly that, and that they're certainly not resistant to fast growth (more than 20% per year).
There's a paradox inherent in the fact that if there's no management at all, informal psuedomanagement appears and that's worse (because it's unstable and must compete to hold ground). What you want is minimalist, benevolent management that operates in the joint interest of the company and its people, but that seems to require a relatively rare lack of ego. You need a cultural shift to a maker's culture where people who build things are held in highest esteem, and the long-term builders/individual contributors have as much influence and credibility as management.
It's pretty rare that one can do away with management outright, though. Someone has to protect the good.