Yep. We (Loomio) have been using Dokku as an alternative to Heroku hosting - our main site is still on heroku, but we know that many people are using Dokku for Loomio hosting.

I spent about a week writing up the documentation: http://github.com/loomio/loomio/wiki

Since doing that we've seen a big increase in the number of poeple contributing code and helping out on Github. It's certainly been worth it from that point of view.