Where using more than one instance would be desirable (I'm not trying to over optimize-- I swear! ;-_-). I suppose one server can go pretty f#€£ing far. But all the clustering requires a license (~$12k per server for start ups?) unless the code which uses it is GPL or AGPL (I think?).
Anyone who wants to explain the AGPL in layman terms would be greatly appreciated. Or specially Neo4j's application of it. To me, it seems cost prohibitive for lean startups, of one or two people.
Again, they've said contact 'em-- so it may be case by case. I could just be worrying about non-existent problems.
I tried Titan and Orient, I didn't find either as nice as Neo4j to use in my code. Though Neo4j, for me, was much more difficult to setup and use as a cluster (at the time).
... And more on topic, I'm about to install Cayley!