I assume you know, understand and take all those threats above into account. But, there are many other threats as well. You browse, filled with certainty that with your correct settings and/or addons, your browsing or even posting will remain anonymous. As long as you only browse, there may not be much danger, if your browser is set up correctly. But if you post any content, the situation changes.
The problem is that even though your posting was indeed done anonymously, the content you posted may allow your identification. How? The way you write, idioms you use, words you use, phrases you use, all that forms patterns that can be compared with already existing material posted on the Internet, by you, when you weren't anonymous. Your identity may then be easily revealed.
The worst thing you can do is lure yourself into a false sense of security, believeing that nobody can ever find out that it was you who wrote that post. Not true. See this article and beware.