Quality of collaborative content cannot be determined a priori. Proof is in the pudding. Sense making is retrospective. So for me the question is content sharing attractive along several dimensions. Is the shared content used to improve the shared space?
Again, like a broken record, I think that neighborhood context can filter our huge amounts of noise and amplify useful bits. The big question is attractiveness. What are the dimensions of attractiveness of FedWiki in neighborhoods?
Safety
Amount, relevance, and cadence of interactions.
User experience with the interface--ease of use.
Stickiness--number of diverse uses for the same tool (fed wiki). To increase familiarity and experienced value.