We have a boy and a girl Berner. We spayed our girl at 6 mo and neutered our boy at 11 mo. We waited until we saw Leo 'lift his leg' to pee, but strangely enough, he rarely does this anyways, for the most part, he squats like a girl. When we had Shady in to a specialist on another matter, he mentioned about her longish legs and tall build and said there was new research that indicates it is better to wait to spay & neuter until a year or even longer, once the dogs have developed more fully into their adult selves. So, I guess the best answer is to not listen to anyone, but do your research and follow your instincts. I think, while females can have their first heat at 6 mo, usually Berners are older, just because they are so much slower to mature. I also think that most breeders are ever so much more knowledgable about the breed itself and it does kind of make sense to me that the dogs should be mostly grown before we intervene.
On another note, it is our Queen of the Castle Shady who puts Leo in his place, by mounting and humping him, not every day, but when he gets too cocky with her. I've only seen Leo do this to one other dog and he was already neutered. He finally met a dog that was less submissive than him and decided to try to be the boss for a change. I think dogs will always work out the social hierarchy on their own but older dogs usually give quite a bit of leeway to pups.