The feed should be public and the dislike button is so I can manage my +/- internets for users who make good/bad posts (negative values for like/dislike is a-ok). I would also like to set permissions in which they can only +/- a user only once. Also, a lot of users who post on the forum are more negatively influenced than positive. So I think the dislike button will have a bigger following than the like button~
For example I have below my vbulletin forum. I can see all the attachments I posted yet I have no way to share them through a feed to external sites.
I believe this would be a strong selling point for Xenforo, increase the reach of your content by allowing users to share externally.