We (DLSS at Stanford Libraries) are planning to use a triple store for storing and retrieving annotations (in RDF) on digital objects. We are currently looking at open-source triple stores such as 4store, Virtuoso, Jena SDB and Mulgara. Are you currently using a triple store or contemplating on using one? How would you evaluate 'your' triple store along the lines of 1) ease of setup, 2) scalability, 3) query performance, 3) bulk load performance, 4) access api, 5) documentation and 6) community support?

Highly appreciate your thoughts, ideas and suggestions.

Thanks,
Ravi Shankar