I've run into some problems with the advanced editing turned on.
I typed a long message (well, a few paragraphs) with it on. When I went to preview the message, only the first paragraph showed. I backed up and tried to do a cut and paste of the original message into the edit window, but it still truncated most of the post.
Finally I turned the advanced editing off and was able to paste the original message into the box, preview it, and post it in its entirety.
Just thought you'd want to know...