I am actually a fan of having a set of acceptance (high level) tests that allows us to test the entire stack at the same time.
Note that acceptance tests are not the same as integration tests.
Right now, our acceptance tests for the front end uses fixtures to stub the server’s response and that requires us to update it whenever we change our backend API. Furthermore, I find that acceptance tests for complicated scenarios are really hard to write as I have to stub every single request made to the server. That to me introduces alot of friction when writing acceptance tests. My ideal scenario will be to have fixtures be created server side and we just assert for behavior of the app as we interact with it via Capybara (for example). One caveat though is that acceptance tests are usually much slow from my experience. Somehow using capybara to click around and waiting for elements to appear takes quite a bit of time.
With all that being said, writing acceptance tests for the entire stack will not be possible if we ever decide to migrate to ember-cli.