While standing doing some photocopying at the 9 to 5, I found myself needing to clear a "mysterious non existant jam" to have a better look at the innards of the copier.
It has a wire drive to control the position of the scanner head, which appears to have virtually no backlash and be very simple, a drum with a fine thread on it, piece of wire wrapped around a few turns in a loop around the scanner head, held in place on the head by similar means to timing belt clamps.
I have also seen this system used to raise and lower the elevator on a 737 so it's obviously a reasonably reliable and accurate system.
Any drawbacks to using this on a large scale machine that's only going to cut light materials? would certainly beat the price and effort of pretty much every other solution I can think of as I can make it entirely out of scrap in the garage!!