For my understanding the "advantage" of the extra bearing options on the cylinder is a misconcept, as someone else said, the "less dust advantage" is the real one. Yes, you can add bearings to the cylinder to support it, but the screw does not get any stiffer from that. And the forces on the screw stay the same, doesnt matter if you rotate the cylinder or the screw.They just move relative to each other in a circular manner. Finally even with a super sturdy rotating cylinder the fores are transfered via the grain to the screw and bent the screw at some point if they are not completely rotational symetrical. At least that's what I was thinking, but a mechanical engineer is also not allways right;)