Mark, thanks.

Switching to an Android device as my main work phone implies using possibly ALL the Microsoft services and software (Exchange/ActiveSync, Office, OneDrive). I'll want to use them as primary services over others.
Microsoft's interest towards the platform is actually one of the reasons for me to consider it instead of the N6. As MS invest more into the Android platform, One Plus may become their preferred one, which I'd be happy about.

As to Google account, of course I planned to use mine, but I actually like it is confined to using Google products and services (also essential to me) and not to just start the phone and start using it. Not a big deal, but I dislike that with Apple, Microsoft, and Google devices. Nice to see this approach here. It just makes more sense to me.

Given the smaller price, I am seriously thinking to go with One Plus. If only screen was bigger and resolution higher.