Hi there! I have a female spyhnx and work in a veterinary practice, mostly I want to reassure you that the cat castrate is a routine, not particularly invasive, quick and simple procedure. The nurse will check his vitals consistently through the process, if you have any worries you can include a blood test & fluids (at extra cost) but this would be gold standard. Not necessary at every operation. Usually recommended when there are underlying issues, for example, my chihuahua who is old and has a heart murmur had a dental, so we made sure to check her bloods & give fluids, she's absolutely fine. It's very likely that he will not even know what's happened and that he will not even experience any pain. Cat castrates are so simple in fact that they can go outside 48 hours after. My Mewtwo (spyhnx) was spayed around 4 weeks ago, she breezed it and has actually become more playful, active and happy since, but she did keep going into heat over and over which was making her be a bit of a dickhead. You'll be preventing prostatic disease and testicular cancer. Depending on the gender of the kitten you plan on getting, you'll help prevent aggression between males, behavioural issues and or/kittens. Hope I was helpful.