I recently tried to get away from outlook as my primary email / calendar. Tried a couple of different providers only to discover just how reliant I am on having seamless calendar invites.
Manually attaching .ICS files to email was not going to cut it. No matter how good caldav is for my phone to desktop, I need to easily make events / respond to them.
Lots of easy ways to get shot there from what I read. Just one more for the list.