E-Brake update. The relay seems to work perfectly. The steppers power on just fine and work as expected. Kill the power and the are still holding. It seems the relays power down before the SKR by a split second. I feel zero drop at all except the slight give it has after power down, the smooth slide.
We are going to call this Plan B, Mike has another idea that could be even better. I will open another thread to discuss it there. E-Brake for Belted Z axis