We are running a critical, high use, Windows IRCXPro network under very difficult network conditions (occasional/intermittent disconnects, times of high latency, bandwidth restrained - not broadband). I am considering shifting from IRCXPro to another server/demon for this capability due to server unstability (combination of network issues and administration issues). We have approximatly 500 users spread out over 12 servers, mIRC will be the client; *nix is preferred for the server, Windows is acceptable. Due to bandwidth concerns, XMPP is not an acceptable protocol. Stability, or the perception of stability, is critical.
What is the recommended server software (including IRC daemon/server settings) for this situation?