For me 4.4.3 is ok.
And battery drain is low.
Installed but booloop. returnet to old 7.0.0
Using 4.3.7.r2 from2 days and ok. Better than 4.3.7.r1
I do this all the time.. back the files in location mentioned above to ext sdcard...wipe device for a clean flash (all except ext sdcard/EFS obviously)...flash new ROM, then flash gapps, then flash magisk, then still in TWRP, I copy the files back...