I would rather use .ear for packaging, as:
- Allows to bundle different SwitchYard composite applications into a single EE application, so developers can work on their specific SwitchYard app in parallel.
- Still there is a single deployment unit for you consumer services, so updating is an all or nothing operation.
At the end, the answer is dependent upon your needs, and the application architecture, so depends a lot on development granularity (as you mentioned), but also in operations (will my services be constantly updated, and if so, do I want a redeployment to affect other services?) Also the binding types play a factor here, as you normally want to deploy some services together depending on the responsibility, on the bindings between services, ...
So there is no single answer here, there is whatever fits better your needs.
My 2 cents.