Just realized when I was answering a longer thread that there is an actual limit on characters even for #premium users. That is when I notice the circle on the left of the world if actually telling you how fare you are in the thread. On this one I am halfway through for exemple.
This thread: 
My reply too long reply:
My reply after I remove a word:
It is 1,000 characters. Up for the 250 or whatever non-premium are limited to.
But then you can add another thread with the second part of the answer/reply.
True that I just wasn't aware there was a limit at all. Good to know.
Yeah. Dont want people turning threads into articles.
Although you can do a threadstorm and get the same impact.