They seem to have problems with too many players active in the same chat channel at the same time. Not certain what makes Novice Network different when it comes to a user limit but a few years ago we were told they were trying to increase linkshell limits to 256 but their testing servers would crash.

Remembering how trade chat from WoW would get on occasion, I'm not certain a global chat is a good idea. It's easy to think that appointing moderators would avoid most problems but players can be prone to abusing any moderation power they're given (see Novice Network on some worlds).

Is there some reason why having a social linkshell or being a member of a large and active FC won't fill the need for you?