What he said. Basically the issue is both peafowl and turkeys are susceptible to the same diseases, but if peacock gets sick, the turkey gets blamed.. when the real blame should go to the chickens, IF they happen to be carriers of the disease that's fatal to both peafowl and turkeys. Chickens aren't much bothered by black head but they still can get it and basically become Typhoid Marys to the peafowl and turkeys.
As for personality and getting along.. I would agree again and say it is iffy. I would never ever pen turkeys and peafowl in the same pen ever again. Nor would I keep the young in same brooder once the turkeys are past one or two weeks of age. Free range, you may expect some fighting between them.. or turkeys being brutal on the peahens, not really letting them get a chance to eat if the food isn't always available.
You will get some responses that say they never had problems though.. so sometimes it will work.. but sometimes it does not work out very well at all.