to the developer
for me to make more traffic is to make the comment more powerful to engage
what I mean is if you see my site and or other site most of them using 3rd party commenting system.
Admin Side:
if the register user comment in some of other user ads (as admin they must be check first before go to "front end" the comment)
if the admin accept the comment and click the unblock the comment,,,, to see in "front end" ,,,,they will be automatic send the notification to the seller that they have comment in there item post...
but if the admin don't like the comment the comment will not automatic send to the seller.
User Side:
my suggestion is make comment see in public but if they want to join the conversation or if they want to comment they must be a register user or must to login first before they comment
also there is recapcha in comment