Mesa 5i25

The specs don't seem to give any pulse timings. However it does say that the max pulse rate is 200kHz which would be 2500nS step + 2500nS space.
In practice there is probably no penalty setting to 5000nS for all timings. That limits you to 100kHz step rate, but even with 32x microsteping that would be 1000rpm motor speed. If you look at the motor torque curves at www.leadshine.com/UploadFile/Down/EM705d_V1.1.pdf you will see that steppers are well past their useful speed at that point.

The pin assignment on the DB25 connector is set by the firmware in the 5i25. This means that you can set up LinuxCNC using the "wrong" breakout board and the LinuxCNC configuration will still be correct. I think that PnCConf has a probotix breakout option, so use that.

Do you know which firmware is actually on the 5i25?