Where are you located, if you dont mind me asking? Are you using a 3G or 4G sim? I am on the china dev rom and applied the standy drain fix from the MIUI forum which helped a lot. I am using a 3G sim and awaiting a replacement (4G capable) sim from my network provider. Just trying to figure out how the latest update might be for me if I update, as I noticed some people on the official MIUI forum saying battery drain had been fixed while others were still experiencing it.