Well, I'm a vendor in the space so I like my implementation: http://stardog.com/ http://stardog.com/ -- and yes we've "tried it" with 10s of billions of edges.

Well, I'm a vendor in the space so I like my implementation: http://stardog.com/ http://stardog.com/ -- and yes we've "tried it" with 10s of billions of edges. Worst cases are prevented from DOSing by having query management features like auto-killing queries that run too long, etc.