Migration is done. Search index has to be rebuilt. That can't be done until we get other tasks caught up. It's going to take a few days for it to stabilize.
The cause of double posting/timeouts has been identified. We need to add more capacity to sql write server. It's partially fixed. I switched our image processing library to GD (from ImageMagick). Animated avatars will only appear inside threads now rather than forum-wide. ImageMagick is holding us back from updating PHP. We're just starting work on search.