Usefull pointer to the use of 3/4 pipe as I have been ruluctant to cut down my 5 ft scaff pipes to 2 ft to get though gaps.
It may be worth looking at the underside of your machine to see what the shape is. While the feet may present a flat wide load area if the roller moves along under a thin steel cabinet wall for example the pressure distribution may be bad for both the cabinet and roller. If that is ok then short 6 in lengths may be easier to move about and cheaper too. Since thin rollers are affected more by grit and concrete roughness shorter ones may reduce that problem.