The ability to set up a dev or test environment to test integration has been a problem with ET in past, maybe it still is (I did Drupal to ET integration several years ago).
However, from what I have seen of Salesforce, which is not direct experience but in watching demos over people's shoulders, their test environment setup is very smooth. I think you have to pay more for it, but you can get a copy of your environment, if you are writing custom plugins it checks that you wrote tests, that those tests pass, and that those tests aren't stubs, before it lets you put anything live. It seemed a legit best practices operation.
Maybe Salesforce can implement that setup for the ET service and APIs. In the meantime I will checkout customer.io for the next project that needs email campaigns.
However, from what I have seen of Salesforce, which is not direct experience but in watching demos over people's shoulders, their test environment setup is very smooth. I think you have to pay more for it, but you can get a copy of your environment, if you are writing custom plugins it checks that you wrote tests, that those tests pass, and that those tests aren't stubs, before it lets you put anything live. It seemed a legit best practices operation.
Maybe Salesforce can implement that setup for the ET service and APIs. In the meantime I will checkout customer.io for the next project that needs email campaigns.