I find that the number of hens has extremely little impact on rooster behavior. I agree, personality and how much room they have are bigger factors than number of hens.
Will they fight? Almost certainly, but you might not see it. They will determine which one is dominant and which one is not. Sometimes this is pretty easily determined and sometimes it is a fight to the death. There will be some refresher courses after you thought this was all decided. Will this disrupt your flock? Maybe, maybe not.
Each flock has its own flock dynamics. A lot of the time when you have two or more roosters, the flock will split and each rooster will have his own harem, especially if you have enough space. I've had three roosters with fifteen hens where one rooster had his harem and the dominant rooster and his sidekick had a separate harem.
I had a flock with two roosters and 18 hens that free ranged. The two roosters hung out with each other more than with the hens. They were both fertilizing the eggs and there was no doubt which was the dominant rooster, but they got along great. There was occasionally a refresher course on which one was dominant, but that never really got very violent.
Sometimes they fight to the death. Usually mine find an accommodation and make a good partnership in taking care of the flock. I cannnot tell you what will happen with your flock.
