first i installed this German firmware (set it for English)...which is very good...in fact i prefer it to oi...then i flashed oi...damn near bricked my n516...or thought i did...went back to this without a problem...then flashed oi again....made it work this time, played with for a bit... then when back to 2.7.2.0 ...no problem at all...
you are now safe to flash between the firmwares...well at least 2.7.2.0