I have a collie, he was very agressive and crazy and kept trying to escape before i got him neutered. I believe if you are not planning on breeding a dog then it is cruel NOT to get him done. my parents had one that they never snipped and he humped everything and went around with a big erection half the time looking miserable. i thought it was quite cruel.
also i thought the op wasn't making a big deal, just a joke about the dog marking - or at least thats the way i took it. the dog will always lift its leg when it pees because its habit, but when its neutered it will stop marking so he won't be peeing on stuff you don't want him to so much, he will be peeing cos he needs to pee! also i don't think that the pee smells as bad - maybe thats just me!
i really did feel though that it calmed my dog down a lot, as collies are like corgis in that they are very highly strung and quite nervous.