The move to my new raspberry pi server is completed. In addition to wordpress, I have owncloud and roundcube installed. With a bit of tuning of the apache-mpm-prefork server (the configuration I used originally) and the installation of php-apc, the performance is quite good.
I decided to move sideways from the cloud. Since the Snowden leaks showed that all cloud-data ultimately seems to end up at some state’s secret agencies, I’ve taken measures to move my personal data (contacts, calendar entries, location information, mails) „out of the cloud“ where possible. And the pi server (€62,50 for the hardware and €3 / month for colocation) is a cheap way to facilitate that.