Let me try rephrasing this:

I am looking for a robust RDF store or library with the following features:

• Named graphs, or some other form of reification.
• Version tracking (probably at the named graph level).
• Privacy between groups of users, either at named graph or triple level.
• Human-readable data input and output, e.g. TriG parser and serialiser.

I've played with Jena, Sesame, Boca, RDFLib, Redland and one or two others some time ago but each had its problems. Have any improved in the above areas recently? Can anything else do what I want, or is RDF not yet ready for prime-time?

Reading around the subject a bit more, I've found that:

• Jena, nothing further
• Sesame, nothing further
• Boca does not appear to be maintained any more and seems only really designed for DB2. OpenAnzo, an open-source fork, appears more promising.
• RDFLib, nothing further
• Redland, nothing further
• Talis Platform appears to support changesets (wiki page and reference in Kniblet Tutorial Part 5) but it's a hosted-only service. Still may look into it though.
• SemVersion sounded promising, but appears to be stale.