I would have to say that male dogs should typically be about 12 months before neutering, and that females is up to the owner, but about 1 year old as well.
My GSD was spayed at 8.5 years old as she was unable to have pups after several breeding and AI attempts when she was younger (pure bred, tracking dog with CKC Championship, certified hips/elbows etc.). She has just had her 15th birthday and has had no real medical issues in life until ~after~ she was spayed. About 8 months after spaying she tore her right ACL... and I suspect that spaying may have had something to do with it. Other than that she is now afflicted with Degenerative Myelopathy, she has had nothing in the way of medical problems.
I feel quite strongly that her physical health and fitness were closely tied to her not being spayed early in life. She had a very good quality diet that was high in protein, and she had a very active life with lots of running, mountain biking, hiking and tracking work. Early life fitness really pays dividends later in life in ongoing good health.
Was having an intact female around ever a problem? No, not really, aside from a little odour and a few blood spots during her heat cycles (about 2.5 times per year). The first heat was smelly, but after that it was not significant problem as she took very good care of herself.
Were male dogs ever a problem? No, not really, even when I spent a year living and teaching on a Reservation where all the male dogs were intact. She would not let them near her (perhaps she had better taste than that in a mate), but she was quite enamoured by the male GSD that the breeder had selected for her. Unfortunately, after several attempts she did not take and we gave up on breeding her.
If I was to get another dog of breeding quality, I would seriously consider not getting them spayed (or neutered).
Please note that many dogs are not of good breeding quality, and it is a very common misconception that it's a good idea to keep a dog intact so that they can be bred - it is not a good idea, and I am not advocating breeding just any old dog.
As for male dogs being hard to handle - some are, some are not. It is up to the owner to get adequate training for themselves and their dog so that controlling the dog's behaviour is not a problem. The one thing that would irritate me about having an intact male dog would be marking - it's really not a very nice trait. But, again, I have seen some dog owners effectively control this in their dogs - so it's all about good, educated owners, who are able to be assertive and in control of their dogs.
These are my experiences and opinions, yours may differ.
NH3