I've dirty flashed this ROM on a Note 7 (lavender). The previous ROM was the stable version. So far, so good. I got rid of the lag I experienced in the stable version (things would sometimes freeze for 10-20s). I used the OrangeFox 11 recovery, and haven't removed the PIN before flashing.
The only things I dislike are theme related, but happened on stable as well: https://xiaomi.eu/community/threads/miui-12-dark-theme-but-white-keyboard.57283/
The only things I dislike are theme related, but happened on stable as well: https://xiaomi.eu/community/threads/miui-12-dark-theme-but-white-keyboard.57283/