Most males of any species are happier without their testicles....everything in my house (apart from the BF....he won't fit in a travel cage) is neutered or spayed. The new guy I just got is sweet, gentle and happy...his are going in the next two weeks lol.
Baxter is the lickiest, sweetest rat in the world....but as he got older and gained his health back he started marking all over the place and wouldn't accept Quinn. Neutered three weeks ago = only marks during intros, is actually getting along rather well in the intros and isn't as nippy.
Quinn was upset with people and generally anxious. Neutered 5 weeks ago = calmer happier manrat
Percy (MRRG foster who is now in his forever home) lost his original cagemate in Dec and was a marky, rat aggressive manrat. Neutered 4 weeks = stopped marking, calmed down around other rats and was generally happier.
Yes, any surgery does have risks, but the more knowledgeable your vet is, the less chance something will go wrong. The benefits (physically and mentally) for an animal being neutered or spayed outweigh the risks. Speak with your vet about your concerns and they will be happy to go over all of it with you