I went with a pretty bare-bones setup using Underscore templates (since they come for free with Backbone) and using the built-in features without additional extensions (like model binding). But I was able to get some fun stuff in there like collection pagination. If anybody would care to take a look and give me some feedback there's a live demo so you don't have to install anything. It's at http://phreeze.com/
I made something similar three years ago, but I admit that even if it was good enough for my freelance jobs, it was nowhere as polished as yours. I really like it. Thanks for sharing.
Mustache-based templates (mustache, handlebars, hogan.js), though they are a bitch in their schooling you on being 'logicless' really are in my experience, very practical.
And please no-one downvote me by nitpicking that templates can never be truly logicless, I know that :)
[0] I wonder if partials count? I don't know that all of the moustache derivatives have them anyway.
But for larger apps Handlebars.js is great because it supports pre-compilation which helps boost performance.
Just to clarify, Handlebars supports server side pre-compilation so that slower clients such as mobile devices can get a bit of a speed boost in the loading process.