nothing major, just that jtv will send out more info if you're set on 3.
Whenever a user joins a channel you're in, jtv will message you with this if you're set on 2
[17:05] Session Ident: jtv (tmi.twitch.tv, nillensbot) (jtv@jtv.tmi.twitch.tv)
[17:05] <jtv> USERCOLOR nillensbot #FF69B4
[17:05] <jtv> HISTORYEND nillens
-
[17:52] Session Ident: jtv (tmi.twitch.tv, nillensbot) (jtv@jtv.tmi.twitch.tv)
[17:52] <jtv> USERCOLOR nillensbot #FF69B4
[17:52] <jtv> HISTORYEND nillens
But when you're set on 3, it'll message you for each message you receive with info such as specialuser.