Might be because mine spend a lot of time free ranging if the predator load isn't too bad. I know that they get around very well when they are 6 months old, but a one year old doesn't. I have never introduced new birds to the flock while they are young so I can't tell you how they do with an introduction, I would imagine about the same as a heritage would react.
If mine are free ranging, I only feed them about once a week to remind them that they live here, the rest they forage for themselves (though I do keep an eye on their condition to make sure they aren't starving). Maybe that is the difference? Mine are putting their energy into finding food instead of picking on each other. But for some reason, even when they are penned up mine don't fight and I don't keep feed in front of them 24/7 because I don't want them to gain weight as fast as possible. I feel it's easier on their legs if the weight gain is slower and I don't want a monster sized bird in Nov. Biggest we ever had was a 27 pound tom at about 6 months old (and at 5 months they were still flying up to perch on a 6' fence). I have hens and toms running together and never had problems, but then again I have only been raising BB turkeys since 1995 so maybe I have just been lucky. Great grasshopper control though!
I just had to combine my flocks due to the roof on one building collapsing. There were three toms and five hens (including a two year old BBB, the rest heritage) in the building that came down. One heritage hen escaped and I haven't seen her since, the BBB hen got a broken leg and had to be put down. The other six were transferred to the building with four BBW hens and two geese, things are still peaceful out there. That will probably change when breeding season hits so as soon as I can find the ground under the snow I need to get to work on temporary pens while putting up another building.