I never understood the "knockout vs backbone" mentality. Knockout binds your UI model to display elements, and backbone binds your server model to your display model.

It can absolutely make sense to have two models for two very different interactions with the same data - UI and REST server calls. Anyone who's written a substantial Silverlight or WPF app already has done this.

Or am I totally crazy? I intend to use both in my latest project, and I'll see how it goes.