I emphatically recommend against Disqus. If users block web bugs (using Ghostery or other browser extensions), Disqus blocks them from viewing any comments and doesn't even present an error message, so users will think there aren't any comments.
Comment on Re^2: Comments Posting - Third Party Software
From two instances of use of Disqus (on Wired & Patheos) that I have seen, a comment is posted multiple times consecutively more often than not. That makes for a bad reading experience.