http://www.yorkietalk.com/forums/gen...n-if-ever.html
Here is the link to the thread I was talking about. It in turn has other links to articles about spaying and neutering.
The question you need to be clear in your mind is ... why neuter him now? Just because the vet mentioned it?
Those articles indicate there is no overweening health benefit to neutering most males.
How-ever your boy is a mature adult, whose growth plates has closed, and that is an important point. You appear to not want any behavior benefit from neutering. Your concern is in main will it change his behaviour that I have grown to love?
There are not a lot of research articles or studies that talk about and have studied in depth neutering of males, vs a vs behaviour alone in mature males. But from what adjunctly other studies have not "noted" is any significant perceived behavioural changes in the adult male. More neutral in terms of behaviour.
So if you want to neuter an adult male to "cure" aggression, or roaming, or marking, or humping..... that is at best a 50/50 proposition.
The chances are pretty good that neutering your male if the surgery is done well should be neutral in terms of his personality.
If there are no other health concerns that would push you to neutering your male, for example like an undescended testicles, or other as yet un mentioned health concerns.
Then the question is really and truly, will you be a responsible male owner, and insure that he doesn't roam? Is not allowed to mate ever?