finally I'am starting the first customer deployment of a TZ 670 and was facing an issue which has to be known. Because the lack of a public known issue list I opened a ticket for this issue, but this is a total unnecessary process for known bugs already reported.
Long story short, I'll post my sightings in this thread to maybe save others some time.
#43566630 SonicOS 7.0.0-R713 TZ 670 After every reboot the setting at Device/Settings/Administration "Failed login attempts before lockout" get reset to a value of 0 which block the ability to save appliance settings. This results "Invalid value entered for 'Failed login attempts before lockout'. Please enter between 1 to 99" everytime when it is not corrected before trying to apply any other Administration setting. This is caused by the loss of the loginFailMaxRate Configuration value, which is correct in a exported configuration before the reboot, but the configuration after reboot has this value set to zero.
If this is something unwanted just make this post vanish.