We recently faced a big challenge by migrating one of our biggest application from Client-Server to a Web architecture. We developed this app by adopting some EMF technologies (such as EMF Edit, Parsley, CDO, etc..) and some good practices like Inversion of Control (with Google Guice) and MVP pattern. And we were really surprised how easily we realized this porting, since we replaced both UI and persistence layers in a matter of a few days.
A model can be represented graphically and textually. While text is able to carry more detailed information, a diagram highlights the relationship between elements much better. In the end, a good tool should combine both, and use each notation where it suits best.
Collaboration is an essential part of developing complex systems. In model-based engineering, for example when using Capella, it involves working with models in addition to source code and other artifacts.