I am all for AI'ing for the reasons that TC already mentioned. Plus it allows you to keep the mares and foals at home where you can keep an eye on them.

ET also has it's place. We have used it on our best mare because she likes to take the 3rd year off. It has allowed her to not carry a foal and yet still have one which saves wear and tear on her body. I will admit that she had an ET done and carried one this year. She is the only one though that really warrants the expense of an ET.

I am totally against cloning though. Those great horses are great for a reason. I feel that cloning cheapens them. I would personally never breed to a clone. But to each their own.