Depends on the table length and the weight of your gantry . There is a reason most tables you see use R & P especially longer than 4 ft. There have been builds with all kinds of drive systems: Rack and pinion, endless loop belt. fixed end belt, leadscrew. chain drive and a couple using small cable and spools. Its all about ratios, belt flex, backlash and acceleration VS Speed. Plasma needs speeds but usable acceleration up to the projected cutting speeds. Using belts you have to deal with the final drive pulley has to be larger than a pinion gear for the belt to stay on the pulley. That changes your drive ratio (lowers torque (acceleration) and adds speed you can't use.