I've try the miui.it and miui.en, so.....my experience was not good, both rom do battery drain so fast! I have MI5 128gb and I know he need more power but, with the last version of the rom I don't see benefit for the battery. This is my opinion, maybe some one had a good experience.
JDC 7.1.2 is the best I tested,and I test all. Fluidity like u have SD835 vanilla droid phone,GPS works,battery reasonably good considering all new ROMs drain battery like it's no tomorrow. *no-support-for-this-app-on-this-forum* is best camera for Mi5 till now. GPS works flawlessly outta box. QC3.0 works outta box.
Both gives me good battery and performance, and costumization. But AEXmod have better thermal throttling management, so you can play games longer without some jaggy lag.
For watching movie it can give you up to 8 hours SOT
For hard gaming usually 4 hours
And daily usage 22 hours standby includes up to 4,5 Hours SOT, full mobile data without wifi. with Facebook, Messenger, Line, WhatsApp, Telegram, Instagram, Tapatalk
AEXmod doesn't give good standby time, usually only 19 hours for me.
JDC nougat also gives good SOT. But lack of standby time, because that's ROMS hard to enter Deepsleep Doze Mode.
Any miui rom + Floppy kernel gives me the best battery.... For AOSP, viper nougat, aexmod nougat is good.... Oreo is not so good in terms of battery... But CrDroid oreo by cc0705(search sourceforge) has given me decent backup....