I decided to try the built-in IPv6 capabilities of mIRC 7.61 (under Windows 10), and noted an issue during my testing.
Identd does not appear to work under IPv6. I've tested this across DALnet's and Undernet's servers and it is repeatable. Is this an issue with the servers or with mIRC? Identd works just fine with IPv4 on the same servers.
Thanks and regards.