Finally, I rooted my mobile phone. I’ve been able to uninstall all the Goggle stuff (Google Play, Gmail, Google+, Google Music) and the phone seems to be more responsive.
Now F-droid is my main software source (open sofware). The only Google app that I’m going to keep installed is Google maps, but without a linked google account.
My owncloud is up and running and contacts and calendar work flawlessly.
It has been easier than I thought, actually, so I’m quite happy with this new freedom.
Ok, I’ll keep you updated.