Funny that you mention this. That was exactly my test case. 
. Twitch must have increased the receiving limit. I got the top100 channel messages with a single connection. I dont know if some messages got dropped becasue i didnt receive a massive amount of chat messages.
The error only oocurs if i am adding more connections. So it must have sth to do with my implementation of the sending limits. 3ventic mentioned that the limits are account related. That is really confusing me. How can you handle than >500 channels, if you want to moderate them proper. Even if you are a verified bot there is a ceiling.