I think discussing work in progress is the core of what many of us might want or need? It's certainly useful, although I also need to get a small group of beta readers to fine tune my work.
Perhaps I am overly cautious, but my suspicion would be that the copyright law is your friend if you have a big publisher behind you, or deep pockets, to make sure it is enforced. Failing that, good luck in pursuing plagiarists through the medium of a foreign legal system. So to be on the safe side, I would keep your work substantially out of the public eye until a publisher or similar has invested in it. Only my opinion, and I am not a lawyer.Ah well, I send copies of my completed novels to various relatives. Mostly encase this pc should self destruct and try and destroy my work! But either way the copyright is yours on an original work, and said copies give proof of when you wrote them