Thanks for your answer.

My requirement is that all my subscribers who may be more than 100, to be able to chat together. I don't understand the difference between public and non public. If those 100 users talk together in a private room will this change anything?
Right not I have the public chat open but is only accessible by a certain user group. This user group however has a lot of members and is expected to grow even more.
Should I look for something else instead of a chat solution? Maybe shoutbox?

Thank you in advance?