I can overclock to 750, but i set 700 now and work very stable @15.50 average.

Are you suggesting that the OC ability is more related to the firmware than the hardware? In other words a batch 2 ought to OC higher when flashed with a batch 1 firmware rather than using the browser trick?
It makes no difference If you flash it with May 18 FW or change the value in the batch 2 FW.. The other member is very luck if he is getting 700 out of a batch 2 Z9 Mini.. I am getting 643 or 650 and i have 1 on 662 max.
I would just flash the May 18 FW and text out what you have..