Speaking of being ambassador - very much yes to do it, very much no to "official status" of being one (since I was called by Rich). IMHO. You are an ambassador or "evangelist" because you do it not because you have a "title" to do it. There is absolutely no benefit or entitlement of being appointed as an ambassador. If you do it, and do it well, you will be known as an ambassador. What else is needed? Why do you need a title?
J.