Right now, I just exposed everything via the directive controller. Although this gives you a LOT of control, it requires you to make your own secondary directive. For now, I actually think this isn't the most terrible thing in the world (because you have a LOT of control over how you want your template to get generated, have no obfuscation around the <textarea>, can customize almost any and all behavior, etc).

That said, I'd be curious to explore an automatic way of translating element attributes into controller property overrides. So <textarea ui-mention find-choices="doSomething"> automatically gets mapped onto the controller instead of the default one. This may involve using bindToController however I was struggling with trying to get it to work and had no real success.