I agree with MannyRibo. I had a Global ROM installed prior to this one, i wiped everything except the SD card and installed perfectly. It's a complete ROM, it's not an addition on top of an old ROM so you do not need those other versions. I even wiped the entire internal memory (it said "no OS installed" at that moment) and i had no issues.
Thanks for comments.
I did a successfull update skipping few ROM versions.
For others who think about update but not yet dare to try: Here is how I made it:
my starting point: version 6.5.5 eu weekly rom and TWRP recovery software preinstalled
(Others might need to install TWRP themselves, I had it allready. Others might need unlock/rooting too, but
I guess most "developer/weekly" versions have that.. and stable official version owners take another route, these steps would not work)
1) made backups:
1.1 settings --> additional settings --> backuo and reset --> local backups --> backup
1.2 booted to TWRP recovery and used its backup option to backup partitions
1.3 rebooted to MIUI and connected phone to PC using USB cable, switched to "Camera (PTP)" mode from phone settings. Choise appear on notification area (seems to need sometime going back to media device mode and back to camera mode to get the connection "live").
1.4 Copied previously created backup files to PC using "export" feature of Mi PC Suite's file explorer
2)
2.1 copied the new rom .zip file to phone's filesystem root using "import" of file exlorer. Safe disconnect of USB cable from PC
2.2 reboot to TWRP recovery
2.3 pick the .zip file and install in TWRP
2.4 after completion TWRP gives two options: "wipe cache and dalvik" and "reboot", choose wipe
2.5 after wipe in TWRP reboot system. It will take long time but new MIUI is starting.
Everything works fine so far.