The composite component suite contains components that are not included in the open source project. These components provide additional rich features for your application while aiding in rapid application development by saving you development effort.
Without any doubt even the open source components will help you a lot in your project. So, you can start immediately and decide later if you need the ICEfaces EE components. For bigger projects ICEfaces EE delivers special servers that help to get a better scaling in your architecture.
You can also have a look at ICEfusion. It also delivers Facelets-based components that are free to use. My book shows how to use them.