When should I step up? How much effort?
Briefly, the first key difference is Integrator adds application-to-application data exchange. For example, one app sends XML to another app using a database. The second key difference is the full control of business processes. Integrator has Business Process Modeling Language (BPML) to speed this development.
EDI maps readily move up, as you would expect. It’s straight forward, but not trivial.
For more information, read about Sterling Integrator.