Addon chat RULES IMHO.
1) Living breathing tech support that is keen and courteous.
2) last update was not way back in 2002 or something..

3) isn't messing with your database / server
4) seems to be an ongoing 'in development' product
Further on that, I don't think its criminal to have developed a software and to just leave it as it is - cool... you sit back and just count the money...but dont expect any interest from me.. With 40,000 + members - I cant be dealing with abandoned software or 'distant' tech support..:erm:
But I am still in a trial period so...
Features missing from Addonchat IMHO are:
Filesharing (that was fun in Flashcat)
Being able to visit the chat in invisible mode (good for Admins to be able to do this IMHO)
So I am still open minded