Cloud, you know the answer more than anyone here, with your paralegal background.
Anyone can sue anyone else for anything. Doesn't mean they will win. But if you are being sued, you still have to deal with the hassle of responding to it, frivolous or not. Why paint a target on yourself?
If what you have said in your blog is obviously the truth, that will increase your likelihood of winning any lawsuits that might be filed against you, and will also tend take the wind out of the sails of anyone who might be thinking of suing you.
Having said all that,
Angies List makes a good case study.
At least one contractor with negative reviews has sued the reviewer.