Is i safe to upgrade BIOS to a routerboard 433 ?
Current mikrotik version is 6.19

Yes, just upgrade and a quick reboot.
I never had any problems with firmware upgrades
Gesendet von meinem HTC Flyer P510e mit Tapatalk 2
Upgrade sucessfull - 20h without problem
Yes, it is safe to upgrade firmware because i had never any issues regarding upgrade.