I use both because I have had straps come loose. I have had parking brakes fail so I do not trust them. Also, race cars do not have parking brakes so we have to put them in gear as a backup. I also believe that there is enough play in the drivetrain that I have a hard time believing that you would cause cylinder wear. I have also never heard my engine builder complain about this on my race motors.
Therefore, I would rather be safe then sorry. Which by the way, I have also had a car come loose on the upper deck and roll half way off.