In regards to him being unchanged with happiness, that's my point. If it makes no difference with him then why do some people say he will be happier?
With what i've read, these were the most common results in studies (to name a few):
-3x risk of hypothyroidism (my vet has also confirmed this with me)
-Increases the risk of progressive geriatric cognitive impairment
-3x risk of obesity
-Increases the risk of prostate cancer (albeit there's an obvious reduction in testicular cancer)
-Increases the risk of bone cancer
-General physical complications with the surgery (small percentage, but still a risk)
I totally disagree with the 3x risk of obesity… my males that were neutered were never over weight, nor were my bitches. Basenjis are quite pre-disposed to hypothyroidism, neutered or not, spayed or not.... and while as said there are pros and cons on both side, you could make the case for each one of them on both sides of the fence. So it is up to each person to make the decision that works for them. For me, as a breeder, I am quite comfortable with my decisions to spay/neuter and to place all pets on spay/neuter contracts.