Can't upgrade from nightly to RC2

Hi. I’ve been running 3.6-beta1-23930 (nightly build) on a production site for a couple of months. I know, not recommended. But I badly needed the Post Formats UI for the project.

Problem 1: I’ve tried upgrading to RC2 using the “WordPress Beta Tester” plugin. But when I activate the plugin I get a message saying Error: Your current WordPress Beta Tester plugin configuration will downgrade your install to a previous version - Please reconfigure it. Is there another way I could safely upgrade?

Problem 2: I realize now that Post Formats UI has been removed from 3.6 core. A sad sad thing, but I’ve got myself to blame for building on nightly code. And I guess I kinda saw it coming…
Anyway. Has the Post Formats UI plugin that is mentioned here not been released yet? And what will happen if I upgrade to RC2 with the mentioned Post Formats UI plugin? Will the video/audio posts I created with 3.6-beta1-23930 still be functional? Or will the Post Formats UI plugin look for the data in other corners of the DB?

What a mess. But perhaps I learned something…