About time. I have bought Nine for Exchange stuff because Outlook for Android just didn't cut it while Nine is basically perfect. I hope this will raise the bar.
Edit : no support for aliases. Well, it's not suitable for me then.
I bought Nine for Exchange some time ago and Outlook still is far behind Nine.
The first thing I wondered about was remote wipe and password policy. Outlook does not enforce them... but still downloads your mail to third-party! That's a big no-no. The very nice feature of Nine is ability to sandbox the remote wipe and password policies to app only - very nice, if you are contractor using your own device with account on your customer's Exchange.
Another thing is Calendar - Nine creates calendar provider and the system Calendar app will display it together with your own. Outlook has its own Calendar and you have to switch between them. You cannot see your agenda in single list. Same with contacts.
Nine also allows encrypting and signing messages.
So far, I don't see any reason switching from Nine. It was 8 EUR well spent.
Per their security policy, the app and servers respect exchange initiated remote wipes see section 3 "User data retention" at https://www.acompli.com/security/
Edit : no support for aliases. Well, it's not suitable for me then.