Speaking from experience, having had 3 males neutered with only minor complications, I think that they do calm down.
Mr. Whiskers and Baby had lived happily together for almost 2 years. I came home to find Baby nearly bald and with bites all over his back, cowering in a corner. Mr. Whiskers, the older and larger and obviously the aggressor, had only a small pierce on his ear.
When we went to the vet to get Baby taken care of, I thought I would just get Mr. Whiskers neutered, but Dr. Fitzgerald recommended getting them both neutered at the same time so that they could recover together and give each other moral support, and possibly live happily again together.
It worked, and they lived happily ever after until Baby died suddenly, from completely unrelated causes.
Mr. Whiskers and I were both so depressed, so I got another young kit, My Little Snuggler. Whiskers was already pretty calm, having been neutered, and still recovering from the loss of Baby. After quarantine, they were successfully introduced and things went well for a while...until the night I came home from work and found Mr. Whiskers cowering in the hidey house.
Well, I immediately separated them and off to Dr. Fitzgerald we went to get The Snuggler fitted for HIS little pink apron!!! He recuperated well, in side by side cages with Whiskers, and eventually they bonded again.
They are now living happily together again, and spend most of their time snuggling with each other, and as I like to say, sharing recipes and baking pies
I remain constantly vigilant and do have an extra cage for when and if...
If done by a qualified, chinchilla experienced Exotic vet, neutering is a relatively safe/minor procedure. And I do believe that they do get the urge to hump a lot less frequently as they get older. Mr. Whiskers is now 7 and The Snuggler is 6.