Changed event using contenteditable=true (V4)

I'm relatively new to coding directly against the CKEditor API so forgive me if there are obvious resources. I googled high and low and couldn't find anything like a comprehensive list of events or a tutorial on basic configuration.

I'm using the new V4 beta and it's beautiful, but I can't seem to find a way to detect when someone has edited content. I can use the DOM "blur" event, and I suppose compare the inner HTML of the element to a prior state, but that seems imprecise and inefficient. Is there some event that fires when content changes have been commited by CKEditor?

Also, do some common events differ under V4? For example, the "instanceCreated" event never seems to fire when using "contenteditable=true". For example, just using this demo from the web:

http://nightly-v4.ckeditor.com/3424/sam ... neall.html

.. and put a breakpoint in the top of this function:

CKEDITOR.on( 'instanceCreated', function( event ) {

}

it is never hit. Yet somehow it's working on that demo - the controls are different for header vs. content type text, as it's supposed to be. Where is the code that is doing this?

Thanks!