I've downgraded from Outlook 15 to 14 (Outlook for Mac 2011), as both were available in my Office365 subscription at the time. Now only 15 remains on the download page, so I'm a bit hesitant to install it and not be able to go back to 14 afterwards.
So if anyone else can help test, I'd prefer that. But if no-one else rises to the occasion, let me know.