Here's another interesting resource which combines the results of a variety of studies and provides references if you wish to do further research. It focuses on mainly health issues, but it does make mention of behavioural issues as well.
http://www.caninesports.com/uploads/1/5/3/1/15319800/spay_neuter_considerations_2013.pdf
One of the posters commented that evidence can be skewed either way - that's true to some extent, but if you are a good researcher you can weed through the studies and get rid of the ones that are biased/don't have enough subjects/didn't follow through for a long enough period of time etc. There's simply no denying that neutering impacts dogs.
When I first got Starr I was certain I would neuter him at 18 months, because I care very much about overpopulation/backyard breeders etc. But I tend to have a scientist's nature, and I wanted to make sure I was doing what was best for my dog. After researching on a regular basis for over two months, I made the decision to leave him intact (with the breeder's permission).
I am very happy with my decision to not neuter him, but I also recognize I am far more responsible than the average dog owner. I am aware at all times he is intact, and I accommodate for that as necessary. It's also worth noting that I'm a dog trainer, and so when he shows behaviours I don't like, I work on them, whereas most pet owners tend to go straight to neutering. It should also be noted that Starr is a performance dog, because that had a significant bearing on my decision as well (for orthopedic reasons). I would, in the future, consider a vasectomy if I knew of a vet who offered it as an option.
Neutering has consequences, just as not neutering has consequences - it's a matter of choosing the path that is appropriate for you. Having an unneutered males means you will have to always be responsible for ensuring he doesn't breed, which means you can't allow him bolt out the door or run away from you. I've been lucky - I don't find having an unneutered male is that big of a deal (he doesn't escape from the yard, he doesn't roam, he can work and train with females with no problems, and he doesn't bark at females in heat), but it will differ from male to male, and a lot depends on you, how you train him, and how responsible you are (and be honest with yourself when it comes to that).
Neutering is a valid option - I just don't want you to go into it with unrealistic expectations of it solving your dogs' fear issues. I think you've gotten a good taste of a variety of points of view on this thread, and I think all posters have valid points - we've made our individual decisions based on different criteria, but we're all looking out for what we feel is best for our dogs.