I didn't make it clear, but Object.defineProperty with getters and setters gets rid of angular.js's traversal needs (I assume, having only looked at angular quite a while ago). There's a few different ways I can think of doing it, I'm just wondering if anyone has yet.

And it also gets rid of the need to hide all your properties in an attributes collection. I'm not sure why you think that's good because it doesn't fire events.

And if you really need ignore properties, you could do something like this:

    var Person = {};
    Person.prototype = new Model;
    var bill = Person.create({ name : "Bill", email : "bill@example.com" }); //adds all using defineProperty and a watcher in get, set functions
    alert(bill.name); //Woo, alerts "Bill", not undefined!
    bill.name = "Bob"; //event fires
    person.special = "blah"; //wouldn't be watched as it's been added after creation
    person.addProperty("special2", "blah2"); //would be watched
    person.special2 = "blah3"; //events now fire with 'normal' access
    var person2 = Person.create({ name : "Bill", email : "bill@example.com", special : "thing" }, { ignore : ["special"]}); //special is not watched

You could even do the opposite and tell it exactly which properties to even bother watching.

There's a reason getters and setters have been added to js, and it's for exactly this kind of thing!