Unless we get a large number of developers to build the same application twice using each framework, all evidence related to this is going to be speculative or anecdotal at best. Having written a lot of both backbone and angular, I can confidently say that I am _much_ more productive with angular, so much that I get incredibly frustrated and resentful when I have to work on a backbone project. I think if you do a little bit of research you'll find a sizeable amount of similar testimony from people who have switched from backbone to a more comprehensive framework.