Thanks - I've been digging around through the data binding internals of these JS libs and I had indeed forgotten about Angular.

I'm comparing details on deferred updates and ease of integrating an OT-type collaboration layer. Derby's already starting to head this way and appears very promising, but I think there are subtle issues both in ShareJS and Derby's implementation. I'm curious how collaboration would work on some of these other libraries, and Angular seems to be thoughtfully architected, if somewhat large.