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.)
Even if you've imported an existing list of contacts, you'll still want an easy way for new fans to join your email list. AWeber's sign up forms provide the perfect solution. Create a simple sign up form for your website, and if you don't have a site, we'll host it for you. Grab the link to your AWeber form and share it on Facebook, Twitter, LinkedIn, or wherever your audience is.