JA Comment installation didn't go so easy for me so I needed assistance. You can measure the level of success of a paid product by the level of support afterward. Joomlart provided professional level support with ticket system for any site concerns I had after installing JA Comment.
I now have a great product, and a site with commenting enabled.
SIGPLUS solved this problem. And it's actually even better than Joomla Works with the embedded slider. Also, fits to the browser, or expands to full size is a nice touch. I love this plugin! :)