Should I or Shouldn't I

I am sitting with a little dilemma. I have a 10 month old puppy and I have to now make the choice of having him neutered or not. The pros regarding getting them out is that he will not mark everything in the house, and he will not be aggressive and he will not be territorial and always running around trying to hump everything. The cons against it is that I am taking out my dogs bullocks. I am removing his manhood. That might also cause him to be more skittish with other dogs, it might cause him to be a soft little puny dog. This is such a big deal for me, yet with Lucca it was a very easy decision to make. Why am I so torn between having them out or not? What is the big deal? A veterinarian once told me that if I am not going to breed with him, I should take them out because they can cause issues in the future. I think I need to do more research into this to find out what the actual medical and psychological pros and cons are. Any suggestions on this will be very welcome!!!