Exactly what I would have said. The humane society has a whole bunch of crocks of crap stirring and their position on spay/neuter is only one of them. I could go on to tell you what I think of these places, but I will spare you guys. Personally I like city pounds much better and if I were to adopt another dog I would be heading there instead of THS.
I recently had to put one of my dogs to sleep. She was my first female dog. She was already spayed when I got her.
I have had many male dogs over the years. One of the dogs I had was fixed when he was 2 years at the suggestion of my vet. He was having pains as he was growing and the vet suggested to delay neutering him so that he had testosterone. My male dog that I have now was fixed at 5 months. I decided to fix him early because he was having behaviour problems and was bouncing off the walls with energy.
I think fixing a dog is really dependent on the owner and the dog. Not everyone should be fixing their dogs at 6 months because the humane society says so. You need to consider your lifestyle, dog's health, and how responsible you are. IMO the vast majority of unwanted puppies are born because of people's ignorance and lack of responsibility. Spay/neuter does not fix this. It is kind of like how people declaw their cats in order to stop scratching. That is just a band aid solution. It is easier for people to mutilate their cat then to train it to use a scratching post. For spay/neuter- well that has to do with lack of responsibility. It is easier for us not to think of our pets and just get them altered. Taking responsibility is out of the question for many people.
Oh and if you want an interesting read on the topic:
http://www.sfgate.com/cgi-bin/article.cgi?f=/g/a/2008/01/08/petscol.DTL
As for me, frankly I do not think I would have much tolerance for a female in heat so most likely I would spay her before her first cycle. I would be very impatient with all the blood and the bee line of male dogs. Plus with my male dog, he may make a huge fuss and be keeping me up all night barking. Its a selfish decision, but one can only tolerate so much.