I have worked with multiple commercial tools in the past, including IBM's Gentran, MuleSoft's Any Point Platform, and we are currently evaluating Altova MapForce along with Smooks, but hoping for an open source solution at this point.
I looked at the java to java example, and it seems to be the same problem: one to one mappings of objects (Order is mapped to LineOrder, and OrderItem is mapped to LineItem). Given that we receive data in many formats from many sources, all which must map to our domain model, this isn't realistic. If I might make a suggestion: your examples are far to simplistic to be helpful in a real-world scenario (at least from my perspective). It would be far more helpful to use real-world examples, or at least closer to real-world. Just a suggestion.
Given what you say and the examples, I am having trouble seeing a use case for Smooks in an enterprise integration engine. It seems like we would need to have another mapping tool in addition to this, which defeats the purpose, since another tool would be able to also do what Smooks does.
Question for the forum: is anyone using Smooks in an enterprise environment, and if so, are you using it just to translate from one data format to the other, or are you using it to map incoming data to your domain model?