I found this post because I was trying to find out what the Pre-NAB announcement was going to be on April 5th regarding Pany Cams. I can't say for sure whether it will be changes to the 300 or 500, but I can tell you it will be (at least) one of these models and that there will be some units available for purchase before June. Hope that helps and thanks for all the tantalizing tidbits.
With what credible evidence can you say this?