[emef]

If using fb for all these use cases is _working_ for people, why would they switch? It's free and ubiquitous, there would be no reason to use something else unless fb fell out of favor en masse.

You haven't been very specific about your use case but it sounds like you may need some critical mass to be successful (chicken and egg problem?). Probably you need word of mouth from a core set of people that love the hell out of your product and will actively convince people to switch.