"Suspenders"

The deploying to Heroku is pretty simple one-line command - I think the major benefit is setting all that up. I don't know how many times I've got my remotes mixed up! But I do complicate things by pushing out to Bitbucket and Heroku. If you've got a few applications on the go at once, you may run out of Heroku space, though. I don't know if it counts the staging and production deployments as two dynos or if it is just one app.

I like Spring as it speeds up migrations and testing as it keeps everything spun up in the background. I like that it automatically restarts the app if anything fundamental changes, meaning you're always using the updated version in development. We've all wondered what's wrong with our new code having forgotten to stop the server and restart it! Spring takes care of all that. The key gain is faster testing. I hate running a full test suite as it loads the server and takes forever for large applications. Again Spring makes that less of a drain on time & resources.