We have done a great deal of testing to make sure the ClickComments work well and will not do unexpected things on users' blogs. As long as it is working well, we are happy.
However, we have never paid too much attention on making sure that it is not completely xhtml1.1 compliant. One of your user Andrei (an expert in the field) has stepped up and help us put it xhtml1.1 compliant. He is good and very efficient. In no time, he's done and it's working well now.
Big thanks to Andrei!