I'm having a weird problem with this plugin, and it's that i'm having an error 502 on all the posts that have 12 comments, not 11 or 13, just 12 comments. First I thought it was happening on random posts, but finally the number of comments was what they had in common. When I modified the number of them, the post worked again.
This error is happening when I see the site logged as admin user. For not logged users, they can see the posts normally, only if they refresh the page (thing that doesn't happen for admin logged users, because they see not cached paged). Perhaps the page again works after W3 Total Cache generates a cached post.