In our area, corn going to feedlots is frequently harvested starting at around 35% moisture. Most cob breakage is from shearing -- split end to end, and not ordinarily a problem in the cage. However, the tapered tip often breaks off separately -- usually carried thru the cage moving sideways. It may be, however, that more distance between the rotor and cage components would allow these tips to upend and be forced into the cage openings. Also more distance may increase the shearing effect off the helical bars. Silks may be another problem -- without pressure holding them against the helicals they may also be snagged in cage openings. Mounting rotor bars at a flatter angle, as I suspect is done on the smaller dia. rotor will probably alleviate some of this. Actually most of this comes from observation of IH machines where the operator has allowed transit vanes to wear down too much,increasing rotor to cage spacing, or concaves are too wide open. Moisture range for this would probably be from about 24% upward.