We had Lycan neutered at 8 months.Our vet advised anytime from 6 months.As already said,it won't necessarily alter their temperament ,but MAY help.If the aggression is testosterone driven,it will help ,but if it's fear driven,then no,it won't .In terms of health benefits,it stops the risk of testicular cancer,(just as spaying reduces the risk of mammary cancer or womb infections in bitches.)
We were told that neutering alters their hormone levels,which means they will be more likely to gain weight,and you need to reduce their food by about 40%. In Lycans case,I would say this is true,he gets loads of off lead exercise,but he did gain weight initially,and now I keep him on a combination of puppy food and low fat food((kibble). I see no difference in his behaviour towards other dogs since neutering,(he is nervous aggressive), but perhaps he would have been worse if he hadn't been neutered,(so difficult to know for sure).As already said,they are all individuals,you will need to weigh it all up and decide what you think is the best for him.