First: wasn't neutering part of your pet onwership contract with the breeder? This is usually not a choice because most responsible breeders always require neutering to avoid their dogs being bred.
Second: over 70% of dogs in the pound are typically intact males. Intact males are more likely to roam, are more likely to get into fights, and are far more likely to die in pounds and traffic accidents as a result. More intact males are surrendered to pounds due to behaviour issues like humping, marking, breaking out of their homes/gardens and roaming, barking. I just counted through the stray dog listings on an Irish welfare site and around 45 are intact males while 16 are females. That is typical.
Third: Marley will always be far more attractive to thieves as an intact dog as he can then be used for breeding.
Fourth: I have seen very few dogs, male or female, altered in any significant way coat-wise by neutering. My males have exactly the same coat they did at age 6 months! I've rarely seen changes in any fit and healthy altered dog. I see lots of changes in fat unfit dogs or those fed poor diets. Most cavalier pets I see are overweight and do not have distinct waists and it is statistical fact that most people have overweight pets and therefor would see coat changes due to this alone. Most pet owners would not even be able to tell the difference in the coat changes that may occur as they are so subtle. A minor aesthetic issue at any rate is far outweighed as far as I am concerned by responsible ownership (meaning preventing unwanted litters and the millions of dead puppies and dogs annually in the US, and the tens of thousands in the UK and Ireland, which for me ALWAYS means neutering (and which every welfare group that deals with rescue dogs or pound always advises and insists on for their own rehomed dogs). I invite anyone who feels otherwise to volunteer in the pound for two weeks, watching how many puppies end up piled in the freezer to be taken off to rendering plants, much less the adults. It is probably the single most sick-making spectacle for any animal lover to see, and the one most likely to make people aware of what their own decisions have the potential to influence. It isn;t OTHER people's responsibility, it is OURS. Cavalier crosses are as hard to home as crosses of any other breed. And unreclaimed stray cavaliers regularly die in pounds in the US and UK and Ireland. Many will not release dogs to rescue, and many times the dogs have probably strayed too far or been stolen and dumped far from home so the owner never checks that pound.
Fifth: I routinely have had to neuter old males at a difficult time for them to have this operation because of prostate problems that frequently crop up in unaltered boys.
Sixth: If you choose to keep your dog intact, a responsible owner can NEVER allow the dog off lead or confined to the house. Such owners are as 100% responsible for avoiding an unwanted litter of puppies as the owner of an intact in heat female. I am so sick and tired of the excuse that 'only females need to be altered and their owners should be the responsible ones'. I wonder if such people have ever done pound rescue and seen how male dogs die in a 3 to 1 ratio to females because so many of their owners took this attitude? Many owners also cannot tell their female has even gone into heat anyway (as evidenced by posts all the time to boards like this!) and aren;t aware of how long the females must be confined or the drive for both sexes to escape when intact... and she will be as rabid to get out and roam to find males as males are if they sniff a female in heat... traveling well over a mile away to find them.
And finally -- I think few breeders will have found that urine ever decreases in smell in intact boys. The owner, however, may get more used to it. Hormones are hormones and the reason males mark and have stinky urine is because they are defining territory etc. This doesn't decline with age.