While I agree on the 100% js. To optimize the experience and app load time its best to provide the data on load inside the document. reducing http calls. backbone supports the idea here:
It is about weighing pro's and con's. I would prefer to take advantage of having all the assets being static, cachable, CDN-able etc. Weighing those options in other apps might not make as much sense, but this particular app for me had small amounts of very user-specific data.
Btw there is still a lot of this 'stack' to be built, I am finding myself having written and having to write a lot of Javascript to support the model I am using