This isn’t an issue of the legitimacy of your business and we certainly don’t have anything personal against your content, however we do have to protect the deliverability of all our customers and the risk associated with these terms is too great for us to take on at this time. Here is a page with more information http://www.mailchimp.com/support/compliance/about-terms-of-use-violation?lptkt=LTK143038471765X
Migration can actually be a major pain in the ass. Although according to aWeber my list was “substantially clean” but I still needed to get all my readers to reconfirm their subscriptions. After a week I’m still waiting for 70% of them to reconfirm. NOT happy. If I stuck to mailchimp I wouldn’t have had these problems. (Their support guys are good though.)
Finally, you can optionally include “automations” with your broadcast. Automations are a simple way to automatically add or remove tags when your subscribers do certain actions, like open the email or click on specific links. Adding and removing tags are important when creating segments, or subscriber groups, and triggering automated email campaigns.