I'm not sure the current implementation of the tiered privileges system is optimal. For instance, after a link I posted got two likes, it become visible to everyone, but it looks like my reply to your comment isn't visible if one isn't logged in. I think that once a non-member link meets the necessary threshold for becoming visible to everyone, the poster's replies to comments in the thread should become visible as well, or otherwise it's just confusing.

Also, I feel that if new contributor comments are hidden in general, that might be a little too discouraging for new people if those comments also need to acquire two member likes in order to become visible.