From my perspective I can only comment on the behavioural aspects in this report and having personally researched and read the studies cited in this report, I feel that many of the studies cited as benefits do not accurately reflect the behavioural impacts of spaying and neutering accurately, particularly pertaining to aggression.  The reason being that many factors throughout a dog's life may cause or contribute towards displays of aggression and none of these studies control for these factors.  It is extremely likely that neutering a male dog will result in decreased roaming behaviour which is directly related to finding  an intact female within scenting range (assuming that the dog already had excellent recall and poor training is not responsible for this behaviour).  You may also find that the dog will be less competitive with other male dogs, but whether this is in an aggressive manner is wholly dependent on the dog in question, socialisation, play skills, social skills etc etc.  You may also find less mounting behaviour, but there are no guarantees here!  Many dogs continue to mount after neutering when they are excited or anxious without there being any reproductive intent - in fact I would say the same holds true of intact males who do not only mount for reproductive reasons.  

Risk wise I would say that castration should never be undertaken for reasons of behavioural change unless under the guidance of a qualified behaviourist, who has performed a thorough assessment of a mature dog¹s behaviour and temperament.  Issues come up when a dog that is fear aggressive around other dogs is neutered to calm him down, in that you remove the natural confidence that testosterone gives the dog - in these cases fear can increase and therefore so will defensive aggressive behaviour.  Equally this natural confidence may also motivate him to explore his surroundings a little more intently (roaming!) ideal in a dog that is anxious within the environment he now finds himself!  I have also found (purely from an observational perspective) that dogs neutered at a young age are more likely to display puppy like behaviours in adulthood, such as squatting to wee and a playful puppy style behaviour in interactions.  This often leads to them being mounted more frequently (I suspect the lack of sexual dimorphism in the dog caused by early neutering inhibiting behavioural development leads to ambiguity in other dog¹s perceptions of the dog) and also getting grumbled at by adult dogs (few adult dogs like puppies that much as they are often rude!.  

From a behaviour only perspective, my advice is therefore to only neuter when you are confident that your adult dog is a happy confident adult with no behaviour issues that have not been fully investigated.  The definition of adult can vary from breed to breed, from 8 months ­ 48 months depending on what your parameters for defining it are, so at a push I would say 2 years of age is a reasonable guideline, 1 is still really too young.  As you can no doubt see from the article, vet opinion on this will vary, so I advise that you to use this article as a basis for an open and honest discussion on the matter with your vet.