I came across a few projects where AngularJS is used along with Sencha Touch (for e.g. https://github.com/tigbro/sencha-touch-angular-adapter). Is there a benefit to using both together? If so, for what? I was under the impression that both of them are full fledged frameworks and you wouldn't have to mix/match.
IMHO, it is not worth the trouble.
Actually, it is very easy to mix other frameworks/libraries into SenchaTouch/ExtJS, and (I assume) people's motivation of doing that is mainly to get the benefit of two-way data binding into ST/Ext.
Things will be fine if you just touch the surface. Your HTML becomes clean and more maintainable, no more "weird" <tpl> tags floating around inside your JavaScript code, etc. The UI part of your project becomes beautiful.
And, you can even easily make data binding sync with simple Ext.data.Model flawlessly.
However, if you're using ST/Ext to handle data communication with backend, you're dealing with Ext.data.Store most of the time. Your collection of data come back from backend into the stores, and your models' hasMany associations are in the form of stores, just to name a few.
Now, how to sync stores with the plain JavaScript arrays or some kind of observable arrays which are used in two-way data binding? What need to be done to stores if the bound arrays changed? What need to be done to bound arrays if stores changed? Adding, removing and inserting are fairly simple operations to deal with, how about sorting and filtering?
Therefore, if you can afford to give up Ext.data.Store, mixing angular with ST/Ext is fairly easy task; otherwise, just stick with sencha.