To handle my comments, I've been using the Javascript/AJAX based commenting system js-kit/echo for years until it closed. Then, I wrote my own AJAX commenting system. It supports several comment threads per page.
It is on github http://github.com/monperrus/jskomment
See also the blog posts of Moparx:
http://moparx.com/adding-new-features-to-the-jskomment-commenting-system
http://moparx.com/implementing-the-jskomment-open-source-commenting-system-within-pelican
Feedback welcome ;-)
--Martin