Well, these articles don't really give completely the same reasons for NOT neutering, so I am skeptical in the face of so many other veterinarians who state differently. There is little doubt that early neutering does lead to taller, lighter chested dogs in large breeds, but I haven't seen any evidence that this is also true with toy breeds, who usually mature sooner.
Your first article talks about all the possible problems of neutering a dog before 5 1/2 months, then makes the big leap of suggesting 14 months as the appropriate time. Huh? Even accounting for individual variation, this seems like a big difference. If you're worried, why not wait until he's 7 months?
All I know is that from what I've seen in neighbor dogs who have not been neutered and from my vet friends who deal with un-neutered males, and even hearing from forum members about marking problems with un-neutered males (and yes, I know that even some female dogs mark) I wouldn't want to go this route.
Additionally, my dog is in consistent, regular, performance training. We have 2 lessons a week, and do Rally run-throughs another day. He's a typical 9 month old distractable NEUTERED puppy. But I see other people there struggling with un-neutered animals, and they are SO much MORE distractable, and that's just not something I'd want to deal with. These are NOT dogs of "the uninformed public" who do not spend time training their dogs. These are dogs, usually show and future breeding dogs, which is why they aren't neutered in the first place, and they are being handled by knowledgable, caring, responsible owners. No thanks. Not for me.
That said, everyone has to make their own decision for their own dog. (assuming that your breeder's contract allows you to wait longer) But I don't think you'll find many people on this forum who have or would suggest waiting that long.