Yesterday Jarvis was castrated - he's 11 years old, and has prostate problems. That's one thing that you're not usually told about. Approximately 92% of entire males have some form of prostate growth in old age and in Jarv's case it was affecting his bowel as it was growing and pressing on it. Would I have neutered him earlier? No - and if we had his time again I would still do the same. And for the record his testicles were absolutely healthy with no sign of any tumours. I knew that though...I'd checked them for 11 years
It enabled him to grow and mature and age as he should. Yes, it's a pain when there are bitches in season but to be frank some of his castrated friends are more amorous than he ever was so that wasn't a good enough reason for me.
Yesterday Jago also went under the knife - thankfully we have a progressive vet who poo-poohed the idea that a dog with an undescended testicle should be fully castrated and just key-holed the retained one out. So he has one healthy testicle and he'll remain entire. His was not hereditary, it was developmental - neither his dam or his sire has ever thrown a cryptorchid pup. If he has prostate issues in old age we'll take that as it comes.
I have seen quite a few early neutered dogs with fear aggression (and who are flighty and difficult to train) and as cockers are usually not the bravest dogs in the world this also has influenced my decision. I had no wish to remove the little bit of testosterone that gives mine a little bit of confidence and maturity.
I think if you are armed with all the information and make an informed decision neither decisions are wrong
For me a very wrong reason would be to neuter a fearful insecure dog - it just manifests itself in more fear
As for bitches, I'm all for neutering them. So many more problems including pyometra and mammary tumours