A new version of the add-in is now available. The significant change is in the installation process, from plain (and simple!) ClickOnce to MSI, as described in my last post.
The new version should load faster (for a start, Outlook 2013 doesn't wag a finger at it for taking a long time, at least not on any of the machines on which I've tested it), and deployment across users and multiple machines should be simpler.