Multiple Namespaces vs One

We are beginning a project to switch over to a differnt EMR for our inpatient system, and we are wondering if others out here have worked on a similar project and how did you handle your Ensemble environment?

Currently, we use one namespace for all of our HL7 interfaces. Has anyone used a separate namespace for a project to keep the build separate until go-live? What were the pros/cons for you using a different namespace? Or did you use one and what issues did you have because of it?