My concern is, Heroku makes add-ons almost too easy, and in my opinion, it may become [for me] a form of vendor lock-in. ... how easy is it to migrate your appl

My concern is, Heroku makes add-ons almost too easy, and in my opinion, it may become [for me] a form of vendor lock-in. ... how easy is it to migrate your application and attached add-ons from Heroku once you have installed / integrated through their platform? Not that hard. Zencoder uses the same API whether you're a Heroku customer or not, and I expect that is true of most add-ons that are third-party services.