I think you hit the nail on the head with this post. Over the past few weeks I have been doing similar research. I have come to the conclusion that there isn't a really great option.

Out of all the frameworks, I am most impressed with Sencha Touch's performance. It was the only one that felt "native" to me.

What I didn't like about Sencha is it doesn't let me use backbone.js, it also looks really difficult to customize the UI if you don't use their "widgets".

Wish there was a better option :(