Shoutbox

This might sound silly but.. How about simply creating a Facebook group and adding in the testers..? Most people already have each other, and you don't need to be friends to be in the same group, ergo you can hide your full info.. Just have everyone send you their facebook username in PM (here) and add them to the group afterwards.

That's what we do for my soccer team. No one see's anyone private info (unless you put your real name on facebook, in which case it's public anyways), and everyone can see all the threads, comments, and even chat with the whole group..