As I already mentioned in my ZNC review "Useful and stable with a but" (https://www.ohloh.net/p/5902/reviews) I really like this piece of software. However, it has one big problem for me while I'm using it. I need more information what ZNC is going on.
From my point of view it's important for all daemons to do some logging. It would be great to have some "I still alive" log entries but much more important are information like "IRC Server XY closed connection" or "ZNC started". With such information I know what happened at any time and can be sure that not ZNC is the problem but rather the IRC network or or the other way around.
By the way, there are a lot of ready to use logging frameworks - so have a look. And for information: I asked already the question if ZNC has some logging abilities and the only answer I got was something like: "You can use ZNC in debug mode". This isn't really an option - sorry.