My biggest blocker by far in moving away, is calendars.

My family has so many interconnected calendars (I personally have 12 on my phone right now) and I still haven't seen that anything else can do what Google does with calendars. My entire family (minus ex wife) is using Gmail on our own domain, and the ex still has r/w access to our kids' calendars (for noting play dates, doctor's appts, etc).

Even syncing Google with Outlook is pure hell - in both directions - and that's before you start adding the interference from employers' firewalls and shit.