If you are in the middle of a meta game, and haven't yet updated, DO NOT update until you have finished and posted your current game. Here is part of an e-mail I received from Stardock on the matter: "Ack...You should always finish your games in the version you started them in." This related specifically to the change from 1.4x to 1.5, so I can't say with any authority whether or not this would be a problem with 1.5x. Better safe than sorry, though. I lost many hours of gameplay, and couldn't post a most excellent game because I overlooked this simple principle.
Perhaps someone with a definite knowledge of the current situation will come along, and either confirm what I have said here, or (even better) let us know that it is no longer a problem.