The ones I have seen who were neutered at 8 weeks, never developed a proper penis. They don't develop muscle and grow too tall. it also seems to have a bad effect on their bone structure. I personally would not adopt a pup like that but that is MHO. I don't like to neuter the males if it isn't needed. People are so paranoid about intact males. I do spay my females though for health reason and for not getting puppies.
To know if you are doing things right, you should be willing to trade places with your dog.