As I understand it, show dogs must be "intact", I think these products are partially aimed at this crowd, including the PermaStay.
Show dogs must be intact because they are potentially the next generation's parents. Neuticles aren't going to be much help there ;-) Permastay - yup, but then if that dog ends up a parent, the puppy buyers are not going to be happy with their puppys' ears. Like the old joke about the couple who have both had cosmetic nose surgery and wonder why their kids have huge noses.
What I heard (urban myth?) was that Neuticles were very popular with women who were totally fed up with a male dog's behaviour but the male human didn't want to get his dog fixed because it was a reflection on his own masculinity. Extreme case, get the dog fixed and neuticled while human male is away. Perfect - dog looks intact, isn't, behaviour and potential paternity suits taken care of, SO still happy with his dog's masculinity. Somehow most women don't seem to take it personally when their bitches are spayed (but we all know how much work babies/puppies are, and there is a small but significant risk in pregnancy for dogs).
Having had a show dog who ended up with testicular cancer, I am strongly in the camp of get a dog neutered at the appropriate age (unless of course he is a show dog at stud). Surgery at 6-8 months is a lot easier on a dog than surgery at 10. Mine took 3 days just to recover from the anesthetic.