Basically it came down to the fact that even with staff they are still to hard to moderate. Also with the constant flow of messages being put across a spambox shoutbox it eats away at band width causing the main system to lag.

Also we have a VM system in place which can act as a messenger system that is more organized then a SB which also gives the user an option to actually report abuse to the system and/or rule violations.

That is if I remember everything correctly. There was more but those were the three main reasons it was shot down.