Does Playstart even work in the content node metadata? If not for scenegraph then it should be noted in the SDK as it is listed implying it ought to work. But yes, I always used seek and it has done its job for me.
Thanks... I feel silly, but it was the variable I was using - pos - that was causing the compile error. So PlayStart *does* work for SceneGraph, but it has the consequence that you can't rewind earlier than that point. So it looks like seek is the better approach anyway.