When comparing IRSSI vs Quassel, the Slant community recommends Quassel for most people. In the question“What are the best IRC clients for Windows?” Quassel is ranked 4th while IRSSI is ranked 7th. The most important reason people chose Quassel is:
Quassal is available for free with source code licensed under GPL and available [here](http://bugs.quassel-irc.org/projects/quassel-irc/repository).
Ranked in these QuestionsQuestion Ranking
Screen multiplexing and remote connection options with screen or tmux.
Allows the modification of IRSSI's look and feel.
Pro Free and open-source
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 Quick and easy setup
3 or 4 commands and you're ready to chat with all your old friends.
Pro Easy logging
Pro Persistent connection
Pro Has a plugin for encrypted communications
Pro Free and open source
Quassal is available for free with source code licensed under GPL and available here.
It's possible for a front-end client or multiple front-end clients to connect to a single core client. This allows setting up an always on-line core that can be accessed from anywhere.
Pro Easy installation on Ubuntu due to the existence of PPA's
Right now Quassel has a PPA maintainer, which allows you to install the stable version or daily versions.
Support for PostgreSQL as database backend and easy to configure for people that know a bit about systems.
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.
Con Cryptic configuration files
Con Potential memory bloat in monolithic client if left running for a period of time
(I don't know if this problem has been fixed in recent years, but I have doubts)
Con No DCC support
DCC or Direct Client-to-Client protocol allows for private communications between users (without the traffic being routed through servers). Neither chat nor file transfers are supported.