I already submitted a repo for some of these. But just add 7 or 8 lens flares and look at them in the editor, the project will crash without much notification as to why. So just be aware of it. It does this in al builds too for us. Because of the shader change (I suspect) I'm finding that particles can cause our game to crash as well. I suspect (but can't confirm because of other ongoing issues) that the particles try to use some shader that U 5.5 hates. I also had a strange occurrence. In one scene, all the Editor-Assigned strings went from my original values (i.e. "Open the Door") to a numbered counterpart ("43215437458465546") while using Text Mode for meta files (reason: GIT). So keep an eye on your Editor strings after conversion. Finally, I found that when U 5.5 crashes - the package sometimes "hangs" trying to load. Much like the building to a non-project folder, it just kind of doesn't say anything. If that happens to you, kill UnityHelper.exe (or delete the Library folder) and be prepared to wait for a very long rebuilding process. I know, Unity wants us to break all of these into different threads - but I didn't (time constraints and not wanting to chase 5 different topics).