For the Rack and Pinion there are issues with any feature where you go X0. As you know X0 triggers the Z axis Probe.
A problems I have faced is connecting via USB and typing in command X0 when the Z axis is low. This makes the Z probe smack the bed. You can accidentally also do this in the LCD Panel and select Go to X0 in the Prepare > Move Axis > Go to X=0
Tonight I found another one... if you use Change Filament when you are printing. This is an owsume thing for us who have a single extruder or like me want to use every mm of filament.
If you hit Change Filament in Tune > Change Filament while printing and are to low in Z you will hit the bed with the Z axis probe. Not cool.
We need a change in the firmware for both these plus one other situation. At the end of a print I have had the printer finish with the X going to 0 when it is too low in Z... this hasn't happened n a while but might need to make sure this doesn't happen.