My company is evaluating the possibility of moving from BackboneJS to AngularJS. As a result, I am in a position where it would be convenient to be powering part of a page's UI with Angular, while the rest of it (the page has tabs, and I want to migrate one tab at a time) is powered by Backbone.
This seems to work fine and doesn't concern me except: because of the way the page is written, the part of the DOM controlled by Angular can be repeatedly destroyed and recreated depending on user behavior (clicking around on the tabs). Every time the content is created, I call angular.bootstrap(). My concern is that this function was not designed to be called repeatedly per page load and there may be unintended, and possibly difficult to detect/debug, side effects.
Since multiple instances of Angular can run on the same page (see here), I think you are safe.