From what a lot of people gathered when the Note 3 came out (I got mine on day one release and the first with Knox) as long as the firmware version being flashed was equal to or greater than the currently installed, you would be fine. That has been case for me, but i suppose there is always a risk something can go wrong.Not true it can trigger Knox. I found out the hard way on my European 8.4 flashing a US ROM. It didn't flash properly (ext4) error and then I had to restore with kies.
Sent from my Nexus 5 using Tapatalk
Sent from my SM-N9005 using Tapatalk