Ajax based commenting system
We have solved this issue with two modules


Ajax Comments



  Provides ajax comments to Drupal sites (commenting like a social networking sites: Facebook, Google+, vk.com etc).



Block Refresh



  Block Refresh allows an administrator to configure a block to refresh it's content via 3 different methods: automatically via a timer (eg every 30 seconds) , manually via a 'refresh' link, and once on page load.


You can view the real sample at http://beinghuman.org/.