They're both using the same virtualization. What's your use case that requires that much CPU? I'd bet spot instances would be a better fit in most cases.
Yup, spot instances would surely fit. And yes EC2 is awesome too. No point in changing the thread to a different discussion altogether. Even if Rackspace is #2, this is not what was expected of it, right? Changing the provider to EC2 is an option that everyone has but that has enormous overhead too!