It works, but you have to use the Prime paid version.
On my phone, disabling the MIUI Optimisation leads to many bad things : some widgets not showing up correctly, app permissions totally f*cked, etc.
Replacing it to On is not enough for the apps functionality becomes normal. You must run app after app and see. Bad for WhatsApp, Telegram and so on.
No root for now, just keeping my flashing forces (and time) intact till AOSP will be on the scene. Patience.
My phone : F2 Pro 8/256