So I’m just throwing out things for consideration.
From what I understand, caponizing is better at a younger age, because the testicles are more friable as an adult, meaning they break apart very easily. Apparently if a bit of tissue is left behind in an adult, a testicle might grow back. If the rooster has already learned crowing, caponizing might not help. There is a big learning curve Even finding the testicles, so should be done by a vet with good experience (or practice on a dead bird). As with any surgery, hemorrhages can occur and there is major vessels near the testicle, again leading back to vet experience. Chickens can be maintained on fluids during the procedure to minimize risk. Special tools are ideal to use working in small spaces. There are pain meds for chickens while they heal. As with all creatures who have been spayed or neutered, they tend to gain weight more easily. As with any surgery going into the body cavity, the surgical risk is always higher.
It seems to me that the surgical risk is tied to lack of experience and learning. A cat or dog spay is no less risky but is done millions of times by vets who have the procedure down pat, extensive research, and proper tools. I wonder if there was a wide call for neutering roosters and it became more than a ‘strange’ request by occasional chicken people for pets, that the procedure would overall be safer, because it would then be taught, standardized, and such?
IMO, I think it would be great if you could take a pet rooster to the vet and get him neutered, Like your pet cat and dog. Animals do not have the same attachment to their ‘junk’ like humans do. But it seems we aren’t their yet. Also to point out, I am not against caponizing for meat or home procedures. I wouldn’t do it myself, and I wish there was a way to give the birds some sort of analgesic or sedative, but that’s not the reality unfortunately.