Some males are really easy to manage and some are definitely, not! Intact males are my biggest pain in rescue; they almost to a dog will pee inside -- or furniture -- and this can make them more difficult to rehome and some people want rid of the dog for this alone. This issue rarely comes up with neutered males.
I think the possible minor health implications of spay/neuter (the statistical risk is tiny) are outweighed by the health benefits (especially for girls -- plus this breed has a significantly higher risk of the risky womb infection pyometra than other breeds according to Swedish research). But especially outweighed by the social benefits. Most dogs are surrendered to pounds and rehomed due to behaviour issues, a lot of of them connected to dogs being intact (marking, humping, straying, fighting, escaping, not settling). I also think the health risks of spay/neuter are a bit of a red herring distraction -- vastly outweighed by larger health issues in the breed that fall into the breeder's domain for action (or non-action) and are largely the result of casual or uninformed breeding by BYBs, or conscious decisions not to follow health protocols like the MVD protocol or to scan to know the status for syringomyelia.
I will take longer legs and a cottony coat any day over an early heart murmur, which will affect half of all cavaliers by age 5, for example
, or a syringomyelia diagnosis, which I have had twice. By contrast, an inordinate amount of concern seems targeted at neutering, based on miniscule risks, and anecdotes about coat changes that clearly have many potential sources.
I'd advise to spay/neuter when it best suits the individual circumstances of the owner and their personal philosophy, after a consideration of the various points of view.
I strongly disagree with breeders who say not to neuter for two other reasons: one is that intact dogs are at far higher risk of being stolen and ending up in the hell of puppy farming. One well known NI breeder found one of her own dogs in just such a scenario and I suspect it may be the one referred to... thankfully the dog was rescued. The second reason is that intact dogs in this breed WILL be used for breeding in pet homes and the breeder loses all control of this once the dog is homed. In Ireland most show breeders don't even place puppies on limited registration to prevent club registration making them a lucrative exploited business.
Given the severe health pressures -- and actual threat to continued survival -- of this breed, no breeder should enable indiscriminate breeding in this way. The one reason to wait may be to MRI/cardiac test pet dogs at an older age to see whether their genes may be valuable.