It's an interesting idea, but I always thought it was best solved by simply designing for the biggest (iPad retina) and using the 'fullscreen scale' option to it scales down for all the smaller displays. Then you also have a single universal app that should work on any iOS or Android device regardless of screen size.
It does use more memory for the images, but on the other hand games which scale up sprites or zoom in will improve quality on the lower-resolution screens, which is a nice touch. It also is a true one-size-fits-all solution rather than having a myriad different options for each possible screen size out there.