Update:
Got the ESS Smooth stepper from Warp9. Connected it directly to my 2 existing BOB's. And after a few tries on the ethernet connection, it works.

So I'm up to 416,6666 steps/mm on the Z-drive and giving a speed of 12500mm/min
Y+1 slave axis, is 400 steps/mm and 18500 mm/min
X axis is 160steps/mm and 25000+ mm/min.

Most of the Z-axis resonance is gone, I guess there will always be some. But much lower noise.

Now is left to find the Acceleration/speed trade off.
Y axis (the worst one) is around 1200mm/s^2 I could set the rapid speed down, and increase the Acceleration.....

Further I need to figure out some 'issues' with the smoothe stepper, but that's a different thread.

Best Regards, Bo Andersen.