Each equity should have its own separate website where users can buy and sell the security.
I think a whitelabel site would be a great idea. git clone, bootstrap and configure, and go from there. Account management would be tough unless there was federation, but underwriters could choose with whom they would federate for quick transfers. If they don't trust or even like you, you don't get to participate in the StarCoin Alliance.
You could rapidly define and ensure a minimum level of security including cold wallets, openid or certificate based auth, a simple accounting backend, etc. by making them out of the box.
Mind starting a thread on features and prioritizing functionality into "can't do without", "important to have", and "wouldn't it be nice?"
That would be super cool and fantastically easier to manage from my point of view...or at least organized a bit better.