My experience of LinuxCNC is that inverting the pins won't do anything for direction of motor rotation.It seems to be an option for those breakout boards that have a logic high configuration.I learned a bit about this on my own home build and while it was great moment seeing the motors turn,it was even more satisfying to see them turn in the correct direction.I got this to happen by switching the connections from the driver modules to the steppers.In the greater scheme of a machine build it isn't a huge thing.Best of luck with the machine.