I don't remember exactly, but I used AOL 2.5 to dial-in and logon. Pretty sure I was using Windows 95.. so that would be mid 90s?

Compliance with the RFC is not a bad thing, unless it breaks things. This does not.

http://rfc.net/rfc1459.html#s4.2.7

Note that the rfc states a check for '@' is only needed when the channel is +i.

csircd behaves correctly, and since moogle updated it to be compatible with TS6, is no longer out-dated.