the roosters are so pretty, I wish I could have a flock of all roos. I had at one time 2 roos (1 std size roo, 1 bantam roo) to 5 hens, but it was 1 roo to 4 hens and I introduced 1 roo and 1 hen. The only time they fought is when the original roo tried to get the new hen that belonged to the new roo. They got along pretty well and the roos would hang out with eachother very well. Occaisionally they would knock the other one off a hen while trying to mount her, but the hens didn't care. If you have enough space and they are a docile roo, then I would think 2 is fine. In a small space, it might not be good.
I was just at a place to pick up chickens that had 3 roos in (what I thought) was a small space. They all looked healthy, a few bare backed hens though. The ratio was about 3 roos to 10 hens though.
I guess it all depends on the breeds too, OEGB's may not do as well as the cochins or wyandottes. All you can do is monitor any new intro's to be sure it goes well and separate if it doesn't. I had 2 roos that HATED eachother, instantly. Even after 6 months of being on the property, seeing eachother from a distance and having thier own flock of hens they still would fight if they accidentally got too close. Funny how the bantams always beat out my standard roo, they are just too fast I guess. I hope your roo's can live in harmony.