Hi Mega,
DevForce is a great choice for large projects. We have many customers that are building complex ERP applications that have hundreds of entities and thousands of screens. The DevForce code generation doesn't clobber the business logic code you've written to extend the entities, so it won't get in your way if you decide to change the schema.
Our architects have been building enterprise applications for over 20 years each, so we have a good idea of what requirements and features are needed in a framework. With that said, if you have a requirement that we haven't thought of, DevForce exposes additional interfaces and hooks for you to insert your logic into the system.