I'm seeing around 11 ksol/s with no OC currently. I'll have to try another work around later like flashing an older version of the firmware.
There is no magic to it, just flash batch 1 firmware and you dont have to do all that random editing and whatnot, you can just select from a drop down menu.
I am curious to see if the batch 3s are even less overclockable than batch 2 or if they have just settled with this configuration as final
UPDATE: I flashed my batch 3 with the batch 1 firmare and am able to overclock this Batch 3 unit to 750 freq. It's only been running 10 minutes so I can't speak to how stable it is; but my batch 2 units will crash almost instantly or 2/3 boards refuse to start hashing above 673 freq. My batch 2 run at 625 freq for about 13.75 ksol/s stable because I had some boards crash with some units even at 631-650.
I will edit this post if I experience any stability issues.
Batch 3 Z9 Mini15 ksol/s stable @ 750 freq
PCB Temps: 64*c ish
Chip Temps: 70*c ish