Nice, sounds like we're using a very similar stack. We are using Jena as our triplestore, but we don't touch the dbpedia triples directly, but rely on Stanbol to do the entity extraction processing for us. And we're also starting down the path of using Quepy.
Jena here too. 14G of data total. Total Triples: 124,294,115 (SELECT (COUNT(*) AS ?no) { ?s ?p ?o })
I believe that's actually pretty big for a triplestore. Seems to work ok, but loading is pretty slow.
I'm contemplating switching to YAGO2[1] or Freebase, but I think I'd be better served doing entity extraction myself (DBPedia & YAGO tend to be out of date).
Great minds think alike? :-)