I just got off a chat session with MS as a result of my battery drain issue after installing Enterprise (see my original thread). Long story short, they said the developers are currently testing the compatibility of the other OS on the Surface 3 to determine if there might be issues that would arise. That is the main reason why it is not yet recommended. So, I guess for now (unless someone reports something different) the Surface 3 won't work in an Active Directory environment since Core can't be bound to a domain.