[pvh]

I'm already building an addon as a Heroku app. Of course, I work for Heroku, so it probably doesn't count.

[judofyr]

You're missing an important detail: Start using the add-on in the Heroku app. Since the add-on provides feature x, you can simply depend on it and remove feature x from the Heroku app :-)

[pvh]

Way ahead of you. The tricky part is being able to bootstrap if the service crashes. It's pretty neat being able to basically provide artificial respiration for your web app in an emergency.