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Would that be more of a "monster" than a standard sized ringneck cock during breeding season? I have been thinking of going jumbo myself next year.
Steve
They really aren't any more aggressive than the standard ring-neck, but the jumbo has (at least mine do) 2 or 3 pounds more weight on him. That extra weight is a lot harder on the hens. I feel bad for the hens as they actually squeak, squawk, or cry (however best describes it) while the larger jumbo is on their back. Even with 6 hens per male, I often have 1 or 2 hens that he will single out and is relentless towards those 1 or 2. The hens back will be bare about 3 weeks into the mating season; which is why I separate them. With only 2 hens now, I have already partitioned a safe haven for my girls in anticipation of this. 
The jumbos weight literally forces the hen on the ground & I fear he will break a hens leg given the football style tackle in which he mounts them. My standard ring-neck was just as aggressive but not as large. I don't like the jumbos temperament during the mating season and I often remove the hens from the male altogether because of this. That's about the only bad thing I can say about them. They really are a joy to have with this one exception based on my own experience with jumbos & standard birds. There are probably some good folks here that have equally bad tales about their male pheasants in the mating season as well. 
Hope that helps... 
Dave & oleduke ( he is my dog lol )
Thanks Dave, that's a big help
Steve