I'm running a production webapp since May on the Heroku EU region, not a scratch since then.
It's a Beta suited for production apps since February:
"Beta Testers,
Heroku Europe is ready to begin running your production apps!
Create an app in the region:
$ heroku create --region eu
Then add add-ons, deploy, and scale as usual. Please note we're still adding
capacity in this area, so contact us if you expect to run more than 30 dynos or
do more than 500 reqs/second on any app in Europe.
As always, private betas should be considered confidential. Please don’t tweet,
blog, or talk about this feature publicly until we announce it ourselves.
Documentation: https://devcenter.heroku.com/articles/regions
Questions & feedback: eu-beta@heroku.com
Best,
The Heroku Team"