Say I have 30,000 VMs deployed in my VMWare infrastructure. I have a good licensing agreement with them and have thousands of applications.

By just shifting workload to AWS without doing anything to the VM, I can save a ton of money. In my case, for every dollar I spend on AWS/VMWare, I could probably avoid spending $2.50 in data center buildout costs and $3 in application rationalization.

With Softlayer, you're inviting IBM into your house, which is rarely a good idea. Give them an inch, they take a mile.