When comparing CIRC vs IRSSI, the Slant community recommends IRSSI for most people. In the question“What are the best IRC clients for Windows?” IRSSI is ranked 8th while CIRC is ranked 26th. The most important reason people chose IRSSI is:
Screen multiplexing and remote connection options with screen or tmux.
Ranked in these QuestionsQuestion Ranking
Pros
Pro "One Identity" ability
Create a personal "bouncer" of sorts, using CIRC "/make-server" (/help make-server for more details) give you a connection so that you can using the same Ident/Nick from multiple devices.
Pro Mobile
Access it everywhere where Chrome is.
Pro Easy setup
Few clicks to install.
Pro Terminal-based
Screen multiplexing and remote connection options with screen or tmux.
Pro Themes
Allows the modification of IRSSI's look and feel.
Pro Free and open-source
Pro Quick and easy setup
3 or 4 commands and you're ready to chat with all your old friends.
Pro Perl scripting
Allows the user to create and use perl scripts to perform actions.
Pro Command line outputs can be sent to a channel or message
/exec -o figlet "Slant.co"
Pro Easy logging
Pro Persistent connection
Pro Has a plugin for encrypted communications
Cons
Con No GUI
Actually a plus for some, lower memory overhead.
Con Gives little direction upfront
Actually, Irssi.org has it's own GREAT documentation for new irssi users. Inline /help options are pretty well documented.