I realize that some may feel my input is irrelevant because I don’t use PG products, but I have participated in lots of different online venues which have commenting on songs as a feature. IMO, the best sites for this allow each song to have its own landing page and collects comments on that page. Every online venue that doesn’t do this ends up with issues of lack of staying power on the first page of posts; which seems to be one of the concerns.

Giving each song a landing page also allows the posters to share information like lyrics, song structure, tools used to create the song, etc.

Trying to put all of that information into a forum AND collect comments AND give thanks for comments is kind of a mess. KVRaudio.com music cafe has the same issue. Post a song there and it can disappear from page 1 in hours never to be clicked on again.

My Songs, photos, writing,etc.
My Sound Cloud