Since we have channels on discuss, I think we could close the IRC channels.
There are not much activities on the channels. And I found it does not worth the maintenance cost for irclog.
The plan would be to keep a ChanServ on the current IRC channels but forbid to join it by setting an invite list limited to administrator. This would prevent the channel to be taken by unrelated people.
As a newcomer I can say that the name “Organisation” on discuss.tryton.org chat channel is misleading. I had access the IRC channel as well, but I had the impression that it was something internal and not a place for a quick question when you get stuck.