Aerie in not Full Stack, as it does not deal with the Model tier of MVC.

Whereas Grails sometimes acts as ‘glue’ for different Java technologies, Aerie attempts to simplify and standardize the web tier of Java/Groovy based web applications.

From the Grails website:

‘Grails aims to bring the “coding by convention” paradigm to Groovy. It’s an open-source web application framework that leverages the Groovy language and complements Java Web development. You can use Grails as a standalone development environment that hides all configuration details or integrate your Java business logic.’

Aerie’s description is:

‘Aerie attempts to simplify the Controller and View aspects of the MVC paradigm in Java based web applications. The key aims of Aerie are: Simplicity, Clarity, Transparency, Consistency and a natural approach to Test Driven Development throughout.’

Aerie tries to minimize the effort spent on the web tier of an Application so that focus can be dedicated to Modeling the Application’s Domain.
As you can see, the philosophies behind the two frameworks are fairly different and, if there had to be a choice, it should be based on a specific application’s needs.

Hope this helps.