If you want to own (and control) your site's comments, then Isso is for you.

It is that simple. :)

Your server, your data.

Disqus is offering you a free service for a reason: they want to make good use of the data that your site comments contains.

They also want to hi-jack the community that you have built around your site - or rather: what Disqus has fooled you into believing that you have.