Hello Admir, welcome to Feng Office Forums!
The 1.7.4 versions have tons of new features and fixes next to the 1.6.2 one (but it does have a tiny bug with the session cache depending on your settings, which has already been fixed for next release).
In my opinion, you should upgrade it. The way we manage the upgrades should let you upgrade from 1.6.2 to 1.7.4 without issues, but, make sure you backup all of your current data in case anything goes wrong.
Best regards,
Francisco