honestly I don't think that I would want to neuter my dog if I were to ever get another male dog. I would never mate my pets, but if I already have spayed females then I see no point in neutering imo.
-that is so odd becoming that way at 6 months - but they do go through a 'fear' period around 5-7 months where something might happen that cause them to be fearful and they never recover. But I have had dogs castrated in this window (6 months) and they were not traumatized by it. Every dog is different, though. OTOH, after 6 months, he is developing his adult personality, which may be very much different from his puppy personality, regardless of being castrated.
I agree - you don't need to neuter your dog if you don't want to with no intact females to worry about, as long as you are always in control of his whereabouts. I always say, "a leash and a 6 foot fence are both good forms of birth control." A responsible owner is in control of their dog, and is in charge of whether a dog breeds or not. I castrated only my males who insisted on lifting their leg in the house. Some lived their whole lives intact, because they had good house manners, and I have never had an unintended breeding. It's all in the animal management. I know MO is unpopular here, but I know we tpfers are able to agree to disagree in a polite manner.
In some European countries it is illegal to castrate your dog unless for health reasons. Interesting.
CAts are a whole 'nother ball o' wax - the males will be impossible to live with if they are not castrated. Spraying everywhere and it is 1000X a more awful smell than castrated cat pee!