Would it be possible to also have a CouchDB as Backend? That would allow every user of an instance to specify his own couchdb database, even different from the irc backend server and have the IRC logged there.
At the moment we have only programmed it to use a mongodb backend. It would probably take about a day though to make a version that uses couchdb.
I've looked into CouchDB a bit recently, but never worked with it. What would be the advantage (for the user) to a separate individual database? And where would the average user set one up? If it requires hosting your own Couch instance on your own server, the audience for that would be pretty small.
Also, consider that the unified DB model does bring with it one big advantage: you can see channel history even when you're not present in the channel.
You can signup with a free couchdb platform such as http://www.iriscouch.com/
I kinda like the idea, but I'm not sure there's a significant benefit to most users. At least when you consider the time investment vs. other issues.
The biggest upside I see is that it alleviates resource/disk capacity stress on a single server. But otoh, it also makes the shared channel logging impossible.