Today I've updated SermonSpeaker.net to Joomla 3.1. If you see any strange things or something is not working as expected, please use the contact form to tell me.
The update itself went quite well. I was using the Joomla Update function and just had to replace the template and reinstall some extensions to get everything working again. It took me about an hour and the actual downtime was minimal.
SermonSpeaker didn't had any issues at all as far as I saw it. Prior to the update I used SermonSpeaker 4.5.6 which is compatible with both Joomla 2.5 and Joomla 3.x. In Joomla 3.1 the Extension Manager then found the SermonSpeaker 5.x update as expected which worked flawless to update.