The behavior you are observing is no related to Kendo UI, but it is specific to how browsers triggers change event. You may use this test page to try it for yourself - open the page in Chrome and IE9 , type something and press Enter.
As you may know, in order to track changes the MVVM value binding listens on the change event of the input element, thus when this event is not raised, the MVVM is not notified for the updated value. You could consider using the data-value-update="keyup", as demonstrated in this online demo, to instruct the MVVM to update the model when user types. Or use the workaround which is mentioned in this forum post.
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