Im afraid there is no definitive answer to your question. The obvious advantages of an enclosed rotor_cylinder are reduced vibration and increased moment of inertia. After that, the advantages_disadvantages are dependent on too many factors to make generalized claims. For example, we had two John Deere conventional combine owners call about corn harvesting experiences. Both operators were in same crop, same conditions, same equipment. Customer A states this cylinder is extremely speed sensitive, I have a sweet spot of +_- 20 rpm that I have to work in to remove the kernel from the cob without damage. Customer B states this cylinder is very forgiving, I can run it as a slow or fast as needed (+_- 200 rpm) and always get a great sample in the tank. The Hyper guys rightfully advocate numerous small, yet compounding improvements to the processor of Gleaner combines to best suit the specific crops and conditions for a genre of combine owners. More than selling steel, we think they promote a philosophy. Unlike some other make owners, Gleaner people are seldom subjected to the O.E.M drivel that altering your harvester is blasphemous. Sunnybrook sells more steel than philosophy. We say thanks to everyone that post on this site, if only because we are rarely criticized and often praised as a company. Merry Christmas to everyone, from all of us at Sunnybrook.