Backend for my project, choosing a NoSQL database

One of the goals of this projects is to have the possibility to work with a NoSQL approach. There are a lot of NoSQL documentation in the Internet, so I only gonna do a brief comments about its philosofity and principes:

• It's not a clear definition about the features of a NoSQL database, there are a lot of tools with differents approaches (document or object oriented, big hashes, ACID and no ACID), 
• A NoSQL database can provide you a huge scalability and high performance. Twitter, Google, Facebook does need this, and your application. Well, about performance, why not?.
• Typically object-oriented applications are builded around the SQL databases, letting the business logic reside in the database and working as simple CRUD interfaces. This is not necessary bad, SQL has its optimizations, performance, specialized teams,... but NoSQL gives you more options to have in mind.

After a short investigation, and following recomendations, I decide to use MongoDB as my first approach to NoSQL databases. My first option was Cassandra, with has a lot of hype around because is used by Twitter and Facebook. Its main features are a descentralized approach, Cassandra is never designed to run as single node but in a bunch of them, and is not ACID compliant.

In the other hand, MongoDB is ACID compliant and is an document oriented database, you can use JSON to manipulate data, is scalable depending on your needs but valid in a single node. It also seems well documented and supported.

A would like to combine with some sort of business DSL (in my next post i'm gonna talk about business oriented development and DSLs) and test two things.

The first one, If my front-end is build in GWT, my business logic in the DSL and  I don't want to use traditional CRUD generation, does I really need Grails building plugins or It's better that i develop another command system around my DSL?

The second is as follows, in many projects there are a considerable amount of repetitive code to access to certain tables (master tables), to display combos, completers, sometimes i18n... Most of this times, this data has no associated business logic, only data retrieval from Database.

Well, if MongoDB can be queried using JSON, and my GWT Front-End understands JSON, is it viable access this tables directly from the front-end? Can this method be productive dropping the repetitive backend code? Would I be acting against layer encapsulation?

I'll let you know my conclusions, give me some time!