As of April 20, 2015, saving and opening files is working well with Google Drive. Excellent development.
And I like "Ask Math Studio" on my IPad, but find that voice recognition is not as reliable as on my Google Nexus devices.
Math Studio 6 is fun to use- but I still prefer the on-line website with my Chromebook. Desmos, GeoGebra, Google Sheets, Wolfram Alpha and Math Studio make a powerful case for using Chromebooks in mathematics education.
Finally, keep up the good work. You have some really great ideas going.